PART 21 - Mike South



Part 21

SKIN DISORDERS

21.1

Skin disorders in infancy and childhood

M. Rogers

Neonatal conditions

Pustular lesions in the neonate

There are many conditions that present in the neonatal period with pustules or pustule-like lesions. Some of these are benign and transient and of no systemic significance; however, many potentially serious infections can present with similar pustular lesions and it is vital to exclude infection in any pustular eruption in a neonate.

Sterile benign transient pustular disorders

Toxic erythema of the newborn

Widespread red macules each surmounted by a papule or pustule; onset in the first 2 days of life and disappear by the end of the first week.

Transient neonatal pustular dermatosis

Onset at birth of flaccid pustules that dry out in 48 hours, leaving postinflammatory hyperpigmentation in dark-skinned infants (Fig. 21.1.1).

Infantile acropustulosis

Crops of spontaneously resolving pustules on the hands and feet during the first few months of life.

Eosinophilic pustular folliculitis of the scalp

Recurrent groups of pustules on a red base on the scalp and later occasionally elsewhere.

Pustular miliaria or sweat duct occlusion rash

Short-lived pustules in among more typical red papules of miliaria, occurring particularly on the face, scalp and upper trunk.

Benign transient lesions simulating pustules

Milia

Firm, white papules especially on the face, which extrude in early weeks of life. These are sebaceous retention cysts.

Sebaceous hyperplasia

Yellow papules on the nose, resolve in early weeks.

Infective disorders presenting with pustules

• Staphylococcal infection

• Folliculitis

• Impetigo

• Candida

• Herpes simplex

• Varicella

Rare disorder presenting with pustules

Incontinentia pigmenti

A linear arrangement of pustules and blisters, particularly on the limbs; important associations are seizures and cataracts.

Blistering lesions in the neonate

There is some overlap between pustular and blistering disorders in the neonatal period. Several conditions may present with blisters and then become pustular.

Infections

• Herpes simplex

• Bullous impetigo

• Staphylococcal scalded skin syndrome

• Congenital syphilis

Other

• Zinc deficiency. Blistered and crusted lesions around mouth, nose and in napkin area

• Epidermolysis bullosa. Blistering in areas of trauma

• Bullous ichthyosis. Blisters on the base of a bright red skin; skin thickens in early days

• Bullous mastocytosis. Blisters on the background of a leathery skin with a peau d’orange appearance

• Langerhans cell histiocytosis. Vesicles and purpuric crusted lesions; a serious disease

• Incontinentia pigmenti. A linear arrangement of blisters

The red, scaly neonate or young infant

A number of important conditions can present with diffuse redness and variable scaliness in the neonate; affected infants often have major problems with temperature regulation and fluid balance and may seriously fail to thrive:

• Seborrhoeic dermatitis. Dull red erythema with a greasy, yellow scale involving particularly the scalp, centrofacial area and all flexures. The scale may be absent in the flexures and secondary monilia is common. Usually asymptomatic and self-limiting after the early months of life. Responds to weak steroids and antimonilial agents

• Atopic dermatitis. Rarely this condition presents in very early infancy with a widespread red scaly and itchy rash. These patients often have food allergies and will go on to develop difficult long-term disease

• Ichthyoses (Fig. 21.1.2). Some of these conditions present with the child covered in a shiny, red membrane that peels off in the early weeks of life to leave a red scaly skin. Some commence with a dramatic degree of redness and scale, without the membrane

• Immunodeficiencies. Patients with severe combined immunodeficiency and other immunodeficiencies may present with a widespread, red, scaly rash in the neonatal period or early infancy. In some cases this represents a congenital graft-versus-host disease

• Staphylococcal scalded skin syndrome. The child is initially bright red and then blisters appear, initially involving the face and flexures and then widespread; these subsequently dry up into scaly crusts.

Birthmarks and other naevoid conditions

Pigmented birthmarks

Congenital melanocytic naevi (Fig. 21.1.3)

These occur at birth as raised verrucous or lobulated lesions of varying shades of brown to black, sometimes with blue or pink components, with an irregular margin and often growing long dark hairs. They may become increasingly hairy with time. Giant-sized lesions may produce considerable redundancy of skin and often occur in a ‘garment’ distribution on the trunk and adjacent limbs. In patients with large naevi an eruption of smaller, but essentially similar lesions may occur during the first few years of life. Malignancy in giant naevi can occur in childhood and the incidence over a lifetime is possibly of the order of 2%. In medium and small lesions the risk is much lower and any development of malignancy is always postpubertal. When large lesions occur over the axial spine, and in particular when multiple satellite lesions are present there is a risk of intracranial lesions, both melanocytic involving the meninges and structural in the posterior cranial fossa.

Naevoid pigmentary disorders

These are flat areas of hyper- or hypopigmented skin, obvious at or very soon after birth. They occur in characteristic patterns – either segmental, or whorled and streaky following the lines of Blaschko. These distributions are now recognized as genetic mosaic patterns. The lesions usually have rather irregular edges. Sometimes the condition is extensive, resembling a marble cake, and both hypo- and hyperpigmented lesions are present in the one individual. These lesions usually occur as isolated phenomena but may be associated, as part of certain mosaic phenotypes, with neurological, skeletal and other abnormalities. An important differential diagnosis is the café au lait spots of neurofibromatosis, which are rarely present at birth and which continue to increase in number.

Mongolian spot

These are flat, blue or slate-grey lesions with poorly defined margins. They may be single or multiple and occur particularly on the lumbosacral area, although the shoulders, upper back and occasionally other areas may be involved. They are found in over 80% of Oriental and black infants and in up to 10% of white infants, particularly those of Mediterranean origin. They usually fade considerably by puberty but may remain unaltered through life.

Naevus of Ota

This is a patchy blue-grey discoloration of the skin of the face, particularly on the cheek, periorbital area and brow. It is usually unilateral and often there is a similar pigmentation of the sclera of the ipsilateral eye. It is most common in Oriental individuals and is present at birth in over 50% of cases. It is a permanent lesion. Associated sensorineural deafness is reported, and very rarely these lesions may be complicated in adult life by development of malignant melanoma.

Epidermal naevi

Epidermal naevi (Fig. 21.1.4) arise from the basal layer of the embryonic epidermis, which gives rise to skin appendages as well as keratinocytes. These naevi have been conventionally classified, according to the tissue of origin, into keratinocytic, sebaceous and follicular types. They can involve any area of skin. They may be present at birth or appear in the first few years of life; they may simply grow with the patient or can extend well beyond their original distribution. On the scalp and face the naevi have a yellowish colour, due to prominent sebaceous glands, and present as a hairless, often linear plaque, usually flat in infancy and childhood and becoming verrucous at puberty.

Lesions elsewhere are usually dark brown but are occasionally paler than the normal skin. They occur as single or multiple warty plaques or lines, often arranged in a linear or swirled pattern. It is now clear that the linear and swirled patterns taken by epidermal naevi follow the lines of Blaschko and that all epidermal naevi can be explained on the basis of genetic mosaicism, with each type of naevus representing the cutaneous manifestation of a different mosaic phenotype. In most patients the naevus is the only detectable manifestation but in some patients there are associated abnormalities in other organ systems, particularly skeletal, neurological and ocular. Skeletal abnormalities occur particularly with naevi of keratinocytic type on the limbs, and neurological and ocular abnormalities with naevi of sebaceous type on the head.

Vascular birthmarks

These can be divided into:

• haemangiomas, which are proliferative vascular tumours

• vascular malformations, which represent fixed collections of dilated abnormal vessels.

Haemangiomas

Haemangiomas usually appear just after birth, undergo a fast growth phase and then, over a long period, tend to spontaneous resolution. It is now clear that haemangiomas, whether superficially or deeply located in the skin, have the same structure, being composed in the early stage of proliferating masses of endothelial cells with occasional lumina and later, as they resolve, of large endothelium-lined spaces. The terms capillary, cavernous and capillary–cavernous are misleading and should be abandoned in favour of the simple term haemangioma.

Superficial haemangiomas (Fig. 21.1.5). These usually appear in the first weeks of life as an area of pallor, followed by a telangiectatic patch. They then grow rapidly into a lobulated, well demarcated, bright red tumour. Rapid growth continues over the first 6 months of life; the growth rate then slows and further growth after 10 months is unusual. After a stationary phase, signs of involution begin, with the appearance of grey areas which enlarge and coalesce. The tumour becomes softer and less bulky and then disappears in 90% of cases by 9 years of age.

Deeper haemangiomas (Fig. 21.1.6). These may occur alone or beneath a superficial lesion (Fig. 21.1.7). The overlying skin is normal or bluish in colour. As they resolve, they soften and shrink and complete disappearance occurs in many cases.

Complications.

• Incomplete resolution – redundant tissue, residual telangiectasia, scarring following ulceration

• Ulceration – full-thickness tissue loss on ‘edge structures’ (lip, lid, ala), inevitable scarring, cicatricial ectropion from scarring of eyelids, cicatricial alopecia

• Obstruction – of eye, producing amblyopia, of nose, leading to difficulty in breathing during feeding, of lip, leading to problems with sucking, of larynx (a ‘beard’ distribution haemangioma is a marker for possible laryngeal involvement).

Management. Simple observation and reassurance while awaiting natural resolution is the ideal approach for most haemangiomas. Indications for active intervention are an alarming growth rate, threatening ulceration in areas where serious complications could ensue, interference with vital structures and severe bleeding. Oral corticosteroids will slow the growth of potentially dangerous or cosmetically serious lesions.

Clinical example

Harriet was born with a blanched area of skin bilaterally on the lower face, extending under the chin. A week later there was a tracery of telangiectases and over the subsequent 4 weeks bright red raised dots appeared in the area, gradually coalescing. When the baby was 5 weeks old her mother, Jane, noticed that Harriet had become very noisy when she was feeding. A general practitioner reassured Jane that this was probably due to ‘a floppy larynx’. The child was referred to a dermatologist to discuss the management of the facial haemangioma. An urgent appointment was obtained and the child was 6 weeks old when it came up. By this time breathing was noisy whether or not Harriet was feeding. The dermatologist recognized this as stridor and arranged a lateral airways X-ray, which demonstrated narrowing in the subglottic area. An urgent endoscopy was arranged and this confirmed subglottic haemangioma. The infant was admitted to hospital and observed carefully. High-dose oral steroids were commenced and after 5 days the stridor had almost disappeared. The steroid treatment was continued over a 5-month period, in gradually reducing doses and Harriet remained free of respiratory symptoms.

Vascular malformations

These are collections of dilated abnormal vessels divided according to the vessels of origin. All vascular malformations are present at birth and grow only in proportion to the growth of the child. They show no tendency to involution.

The most appropriate terminology refers to the component vessels and many outdated terms (in brackets below) can be abandoned:

• Capillary malformation (port wine stain, Fig. 21.1.8) – flat purple stain, most commonly on the face but may occur anywhere

• Venous malformation (varix) – bluish tumour, empties with pressure and when elevated; fills when dependent; phleboliths may develop within it

• Lymphatic malformation (lymphangioma, cystic hygroma) – macrocystic deep lesions present as skin-coloured tumours, often with bruising; superficial microcystic lesions present as groups of haemorrhagic vesicles or warty lesions

• Arteriovenous malformation – skin-coloured lump that may expand, become painful and bleed at puberty

• Other mixed malformations.

Moles (acquired melanocytic naevi)

These usually first appear after the age of 1 year and increase in number throughout childhood. They commence as brown or black macules, some of which become raised and enlarge laterally as they develop. They are usually of uniform colour and well circumscribed. The risk of melanoma arising from acquired melanocytic naevi is very low (less than 0.1%); melanoma almost never occurs in childhood so their prophylactic removal in young patients is not justified.

Halo naevi

A depigmented halo may occur around a melanocytic naevus; the lesion may appear inflamed and often disappears, leaving a white spot, which may eventually repigment. This is a completely benign change.

Dysplastic or atypical naevi

A subtype of acquired melanocytic naevi with characteristic clinicopathological features and a marker for an increased risk of developing malignant melanoma. They differ from more typical moles by being larger (more than 5  mm diameter), having irregular and indistinct margins and irregular tan brown coloration, often with an erythematous component. They are predominantly macular, sometimes with a central elevated portion. They may appear in childhood as small, typical-appearing naevi which after puberty develop the atypical features. Characteristic dysplastic naevi may appear on the scalp in childhood. The final confirmation is based on the finding of some or all of a constellation of histopathological features. Patients with multiple dysplastic naevi should be observed frequently and monitored with serial photography. Any such naevus showing significant alteration should be removed immediately.

Cutaneous infections and infestations

Mollusca contagiosa

This is a poxvirus infection that is rare under 1 year of age and occurs particularly in the 2–5-year age group. The spread of lesions is enhanced in warm water and outbreaks occur among children who swim together or share baths or spas. Further spread of mollusca in the individual is also encouraged by being in warm water.

Clinical features

• Typical lesions are spherical and pearly white with a central umbilication, but they may vary from tiny, 1  mm papules to large nodules over 1  cm in diameter. They occur on any part of the skin surface, with common sites being the axillae and sides of the trunk, the lower abdomen and the anogenital area. Rarely they occur on the eyelids, where they may cause conjunctivitis and punctate keratitis

• A secondary eczema often occurs around lesions, particularly in atopic children

• Secondary bacterial infection may occur, producing crusting, redness and pus formation. However, these same changes may be seen during spontaneous resolution, which occurs in most within several months, leaving normal skin or small, varicella-like scars

Management

Each lesion lasts for only weeks and, if the child is kept out of heated pools and spas and has showers rather than baths at home, the proliferation is curbed and the number of lesions usually decreases quickly. If these measures are rigidly adhered to, treatment is rarely required:

• mollusca are surprisingly resistant to chemical therapies

• the most definitive treatment is deroofing of the lesion with a large cutting-edged needle and wiping out the contents

• with multiple small lesions in a young child, spontaneous resolution should be awaited but, if the lesions are troublesome because of their site, surrounding eczema or frequent secondary infection, removal under nitrous oxide sedation may be considered.

Warts

These are benign tumours caused by infection with a variety of papilloma viruses of the papova group:

• the common wart (verruca vulgaris) occurs particularly on hands, knees and elbows

• plane or flat warts, 1–3  mm, pink or brown, barely raised papules, occur on the face and often spread along scratch marks or cuts

• plantar warts occur particularly over pressure points on the soles and can be differentiated from calluses by a loss of skin markings over the skin surface

• warts at mucocutaneous junctions often have a filiform or fronded appearance

• anogenital warts may be acquired from maternal infection during delivery but their presence should always raise the suspicion of sexual abuse

Management

Various forms of treatment are available; they depend on the area, the type of wart and the age of the patient. Because spontaneous disappearance is common, aggressive treatment is often inappropriate. Treatments include:

• keratolytic wart paints (e.g. salicylic acid, lactic acid and collodion) – for common warts and plantar warts

• retinoic acid preparations – for facial plane warts

• podophyllotoxin and imiquimod – for anogenital warts, used under strict supervision

• a 20% formalin solution – for plantar warts, combined with serial paring

• cautery or diathermy – useful for lesions on the lips or anogenital area but elsewhere recurrence is fairly frequent following their use and there is also a risk of producing a painful scar, particularly over the joints of digits or on the palms or soles

• liquid nitrogen cryotherapy – a successful method of dealing with common warts that is useful for older children.

• oral cimetidine – has recently been demonstrated to be a useful treatment in some cases of multiple refractory warts.

Dermatological presentations of herpes simplex

Herpes simplex virus (HSV) infections are extremely common in children, and serological studies confirm that more than 90% of the population have been infected by the time of reaching adulthood. The commonest type is HSV1, although HSV2 is more important in adulthood, being the cause of genital herpes. Several distinct presentations are recognized in childhood.

Intrauterine herpes simplex

• Cutaneous lesions include blisters and erosions, sometimes in a dermatomal distribution, and irregular, often linear scars

• Other features are microcephaly, short digits, cardiac abnormalities and a variety of ocular abnormalities

Neonatal herpes simplex

• The skin lesions are grouped blisters, localized initially on the presenting part, usually the head, with the onset usually between the fourth and eighth days of life. The eruption may become widespread, with individual lesions a few millimetres across coalescing to produce large erosions

• A rapid immunofluorescence test on material from the blister base enables a diagnosis within a few hours

• Assess immediately for the presence of and extent of other organ involvement, of which the most potentially devastating is neurological

• Immediate treatment with intravenous aciclovir is indicated.

Primary herpetic gingivostomatitis

The child is systemically unwell with a high fever and there is severe swelling, erosion and bleeding of the gums and the anterior part of the buccal mucosa. Spread to the lips and the facial skin often occurs. There may be considerable soft tissue swelling and prominent lymphadenopathy. See also Chapter 14.1.

Primary cutaneous herpes simplex

• Can occur anywhere on the body, depending on the source of infection; painful grouped blisters or pustules on an erythematous base that soon break to produce erosions or crusted lesions

• Often there is local swelling and regional lymphadenopathy and the child may be febrile

• When a primary lesion occurs on the thick skin of a finger, the blisters do not break easily and intact, grouped pustules last for several days

• When primary herpes simplex occurs in the napkin area it presents as a severe erosive napkin rash. This is usually contracted from a herpes lesion on the lip of a carer, directly or via the hands, but occasionally occurs as a result of sexual abuse.

Recurrent cutaneous herpes simplex

• Recurrent herpes simplex of the face, particularly around the lips (herpes labialis), is common in childhood. As in adults, various factors, including fever and sun exposure, may reactivate the virus

• Recurrent herpes on a finger, presenting as long-lasting intact pustules (Fig. 21.1.9), is often mistaken for a recurrent bacterial infection.

Disseminated herpes simplex (eczema herpeticum)

This occurs as a complication of atopic eczema and in immunosuppressed patients (Fig. 21.1.10). It may originate from a primary or recurrent infection or from external reinfection. Spread is both on the surface of the skin and also by haematogenous dissemination. The lesions are vesicles or pustules 2–4  mm across, which may spread with alarming rapidity and have a tendency to coalescence to produce geographical-shaped erosions with scalloped edges. If there are more than very few lesions the patient should be hospitalized. Secondary bacterial infection should be treated with oral antibiotics and saline or tap water packs used to relieve discomfort and dry out the lesions. In severe cases, systemic aciclovir is indicated.

Indolent ulceration in the immunosuppressed patient

An unusual presentation of herpes simplex in immunosuppressed patients is as a chronic, slowly growing ulcer, often with rather overhanging edges. The outline is usually irregular, reminiscent of the geographical shapes produced by coalescing lesions in the more typical forms of herpes simplex. It requires systemic antiviral therapy.

Impetigo

Impetigo is a bacterial infection caused by Staphylococcus aureus, group A streptococcus or a combination of these organisms; it occurs in two forms, bullous and non-bullous (or crusted).

Clinical features

• Bullous impetigo (Fig. 21.1.11) is always due to staphylococci. Blisters arise on previously normal skin and increase rapidly in size and number, soon rupturing to produce superficial erosions with a peripheral brown crust. The erosions continue to expand, sometimes clearing centrally to produce annular lesions.

• Non-bullous impetigo may be due to either organism or to a combination. The lesions begin with a small, transient vesicle on an erythematous base. The serum exuding from the ruptured vesicle produces a thick soft yellow crust, below which there is a moist superficial erosion

• Impetigo is often superimposed on other skin diseases such as insect bites, scabies, pediculosis and atopic eczema

• Staphylococcal impetigo does not scar but deep streptococcal lesions may

• Postinflammatory pigmentation can occur, particularly in dark-skinned patients.

Management

• Saline bathing may be used to dry out the lesions

• A swab for culture and sensitivity testing should always be taken

• Topical mupirocin may be successful for localized early disease

• In general, oral antibiotics should be used. Because of the rarity in most areas of pure streptococcal impetigo, a penicillinase-resistant penicillin (e.g. flucloxacillin or Augmentin (amoxicillin plus clavulanic acid)) or erythromycin are the treatments of choice while awaiting culture results

• If a group A streptococcus is isolated the patient should be treated with penicillin and watched for 8 weeks for signs of glomerulonephritis.

Staphylococcal scalded skin syndrome

Staphylococcal scalded skin syndrome (Fig. 21.1.12) is a widespread blistering disease caused by the epidermolytic toxin produced by certain strains of Staphylococcus aureus, most often of phage group 2, types 70/71 or 51 but occasionally of phage group 1. This toxin produces a superficial splitting of the skin, with the level of split being high in the epidermis. Clinical disease occurs when there is sufficient toxin load produced from an infection with these organisms.

Clinical features

• The commonest sites of infection are the umbilicus (in neonates), the nose, nasopharynx or throat, the conjunctiva and deep wounds

• The condition commences with a macular erythema, initially on the face and in the major flexures and then becoming generalized. The skin is exquisitely tender and the child draws back from contact. After 2 days flaccid bullae develop and the skin wrinkles and shears off. The exfoliation is most marked in the groin, neck fold and around the mouth and may involve the entire body surface, but mucosae remain uninvolved

• The child is usually febrile but, because of the superficial level of the split, fluid loss is rarely significant. The erosions crust and dry and heal with desquamation over the next 4–8 days leaving no sequelae

Clinical example

At the age of 13 months Oscar developed conjunctivitis. Oral amoxicillin was prescribed by his GP. 4 days after commencement of this Oscar developed a red, macular rash on his face and in the groin and axillary areas. Oscar was febrile and irritable and screamed when his mother tried to pick him up. The rash was diagnosed as a drug reaction and the antibiotic was ceased. The red rash continued to spread and flaccid blisters appeared in the groin, with the skin lifting off easily. A Gram stain from the blistered groin skin demonstrated no organisms. By this time the result from the conjunctival swab had returned, demonstrating Staphylococcus aureus insensitive to penicillin but sensitive to flucloxacillin, which was immediately commenced. The rash worsened over the next 12 hours, with sheeting off of skin all over the body, most marked around mouth and in axilla, groin and neck fold. The child was brought to a paediatric emergency department, where a diagnosis of staphylococcal scalded skin syndrome was made and intravenous flucloxacillin was started. Over the next 4 days the redness settled, the blisters dried out and Oscar became comfortable and cheerful. He was discharged on oral flucloxacillin for a further 4 days.

• Cultures from skin and blister fluid are usually negative. Cultures should be obtained from any area of obvious infection but, if none is apparent, from nasopharynx and throat.

Management

• Nurse the child naked on a non-stick material and handle as little as possible

• Avoid topical agents in the early stages

• A penicillinase-resistant penicillin (e.g. flucloxacillin or Augmentin (amoxicillin plus clavulanic acid)) is the treatment of choice and is usually given intravenously

• Analgesia is often necessary in the early stages

• Emollients are useful once the skin dries and desquamation commences

Boils (furuncles)

Boils are cutaneous abscesses, centred on hair follicles, caused by certain species of coagulase-positive Staphylococcus aureus.

Clinical features

• Local predisposing factors are cutaneous injury, friction and sweating

• Episodes are often recurrent and many patients with recurrences are found to carry furuncle producing strains of Staphylococcus aureus in nostrils, axilla or groin or to have had close contact with someone who does.

Management

• Early lesions should be treated with warm compresses and oral penicillinase resistant penicillins penicillin (e.g. flucloxacillin or Augmentin (amoxicillin plus clavulanic acid)). Erythromycin may be used in patients allergic to the preferred antibiotics

• For older lesions which have matured and pointed, incision and drainage may occasionally be indicated in conjunction with the use of antibiotics

• Chronic and recurrent furunculosis should be treated with a course of antibiotics of several weeks duration. While the patient is on antibiotics, all clothing, towels and bed linen that have contacted the affected areas should be washed in hot water. Attempts should be made to deal with the carrier state in the patient and/or close contacts. Washing of the groin, axilla and hands with an antiseptic soap can help, as can topical nasal antibiotics such as mupirocin. An oral rifampicin and fusidic acid combination has also been successful in reducing carriage.

Streptococcal perianal disease

This is a distinctive perianal eruption due to group A beta-haemolytic streptococcus (GABHS):

• peak incidence is in children 3–4 years of age but it may occur in infants

• a likely mode of transmission is digital contamination from an infected oropharynx, although symptoms of pharyngitis are rarely present

• the child complains of pain on defecation and often refuses to open the bowels

• bright blood is frequently seen on the stool. A bright pink erythema extends from the anal rim, which is often fissured and macerated, 2–3  cm out from the anus; the skin is tender but not indurated

• lymphangitis and lymphadenopathy are absent

• there may be an associated GABHS balanitis or vulvovaginitis

• diagnosis is established by culture, on blood agar, of GABHS from a swab of the perianal skin

• the treatment of choice is oral penicillin V 50  mg/kg per day in four divided doses, combined with the use of topical mupirocin twice a day. Recurrences are very frequent without this combined therapy, which should be continued for 10 days. Erythromycin is appropriate in penicillin-allergic patients.

Tinea

This is an infection due to dermatophyte fungi; the source of the fungus is an animal (e.g. dog, cat, guinea pig, cattle), the soil or another human. Tinea occurs on any part of the skin surface and can involve hair and nails.

Clinical features and diagnosis

• Classical features of tinea on the general body skin are itch, erythema studded with papules or pustules, annular or geographical lesions with a tendency to central clearing and a superficial scale (Fig. 21.1.13)

• Tinea is often unilateral and always asymmetrical, whereas eczema and psoriasis, which it may resemble, are often symmetrical in distribution

• Between the toes maceration with a thick white scale is the main finding and an annular lesion may extend on to the dorsum of the foot

• Nail tinea produces a white discoloration and crumbling of the nail plate with an accumulation of subungual debris

• On the soles there are deep seated blisters or pustules that dry to produce brown crusts

• On the scalp there is a characteristic combination of alopecia and inflammation with the hair loss being due to breaking of the hair shafts. Depending on the pattern of hair invasion by the fungus, the hairs are either broken off flush with the scalp or at lengths of up to 2–3  mm, but in an individual case all the hairs break at the same length. The inflammation varies from mild erythema and a fine, dandruff-like scale to a pustular carbuncle-like lesion (kerion)

• A Wood light (an ultraviolet lamp) is useful in the diagnosis of some varieties of scalp tinea, with the infected hairs fluorescing bright green. Other varieties of scalp tinea produce no typical fluorescence and the Wood light has no place in the diagnosis of tinea on the skin surface

• The diagnosis of tinea is confirmed by scraping hairs or scales on to a slide, adding 20% potassium hydroxide and examining the specimen microscopically. Septate branching hyphae are seen in skin scales and spores are found in hair. The fungus can be cultured on appropriate media.

Management

• Topical antifungals may be satisfactory for small, localized patches of tinea on the skin

• Oral griseofulvin is the treatment of choice for long-standing or severe cutaneous tinea and hair tinea. This fat-soluble drug is best taken after meals, preferably with a glass of milk. In general a 3-month course is used

• Nail tinea is particularly resistant to treatment and may require other antifungals such as terbinafine.

Tinea versicolor

This is an infection with Pityrosporum species, which are part of the normal skin flora. It occurs mainly in tropical and temperate zones and usually affects adolescents and young adults.

Clinical features and diagnosis

• Presents as well demarcated, asymptomatic or slightly itchy macules with a fine, branny scale that is often only obvious on light scratching of the lesions. Primary macules 1–10  mm in diameter coalesce into larger patches

• Lesions occur in two colours – red-brown, especially in the fair-skinned, and hypopigmented in darker-skinned children

• The hypopigmented form must be differentiated from vitiligo, where the depigmentation is total and scale is absent, and pityriasis alba, where lesions are less well demarcated and some erythema may be seen

• In young children it often presents with only facial lesions and almost invariably a parent or older relative will have tinea versicolor in the typical distribution

• Diagnosis is confirmed by microscopic examination of skin scrapings to which 20% potassium hydroxide has been added. Grape-like clusters of spores and short fragments of thick mycelia are seen.

Management

• Untreated, the condition is persistent, although some improvement may occur in winter

• The treatment of choice is with topical imidazole creams

• With the depigmented form, therapy deals with the scale but sun exposure is required for full repigmentation

• Rarely in severe disease in adolescents a short course of oral ketoconazole is required

Scabies

Scabies (Fig. 21.1.14) is due to Sarcoptes scabei, an eight-legged, oval-shaped mite less than 0.5  mm in length. The disease is transmitted by close physical contact, with transmission by fomites being exceptional. A small number of mites burrow into the skin in certain sites, particularly between the fingers, the ulnar border of the hand, around the wrists and elbows, the anterior axillary fold, nipples and penis and, in infants, the palms and soles.

Clinical features and diagnosis

• The pathognomonic primary lesion, a typical burrow, is rarely seen. It is a 2–3  mm long curved grey line with a vesicle at the anterior end

• Other lesions that mark the sites of burrows are small blisters or papules, larger blisters on the palms and soles of infants, scratch marks, secondary eczema and secondary bacterial infection

• Eczema or impetigo in the target areas for scabies should always raise suspicion of this disease, as should blisters on the palms and soles of infants

• Often more prominent than the evidence of burrows is the so called secondary eruption of scabies. This presents as multiple, very pruritic, urticarial papules, which are soon excoriated. They occur particularly on the abdomen, thighs and buttocks

• Large inflammatory nodules may form part of the secondary eruption, occurring particularly on covered areas, especially on axillae, scrotum, penis and buttocks. They may, however, be very widespread, producing diagnostic difficulties. They may persist for months after effective scabies treatment

• The diagnosis of scabies is usually a clinical one but can be confirmed by demonstration of the mite. A burrow, which may be softened by the application of 20% potassium hydroxide, is scraped and the material is smeared on a slide for microscopic examination. Burrows may be more easily identified by rubbing a thick, black marking pen over suspicious areas and wiping with an alcohol swab, leaving a burrow outlined with ink.

Management

• The patient and all close contacts should be treated simultaneously

• 5% permethrin cream is the treatment of choice and should be applied to all body surfaces from the neck down and left on overnight. A repeat application should be administered after 1 week

• In extremely young infants 6% precipitated sulphur is preferred

• Bedclothes and clothing should be washed in the normal way with no disinfection required

• An irritant dermatitis may follow scabies treatment, particularly in atopic children, and may require emollients and topical steroids once the miticide therapy is fully completed

• Persistent nodules may respond to topical corticosteroids but a coal tar solution painted on is preferable for the very resistant ones.

Pediculosis

Human lice are six-legged insects without wings, grey in colour or brown-red when engorged with blood. The body louse and the head louse have a thin body 2–4  mm long and three similar pairs of legs; the pubic louse is wider and shorter and the second and third pair of legs are larger than the first, producing a crab-like appearance. The ova (nits) appear as oval, grey-white, 0.5  mm specks, attached by a firm chitin ring to hairs or clothes.

Pediculosis capitis (head lice)

This is a common infestation, often occurring in epidemics in schools. The occipital area of the scalp is preferentially involved and may be the only site affected. The condition is itchy, leading to scratching with excoriations and also eczematization and secondary infection, which may mask the underlying infestation. Permethrin shampoos are effective pediculicides but may not destroy ova and a repeat application after a few days is recommended to kill further hatched lice. Removal of nit cases with a fine comb is easier if the chitin is softened by a prior application of vinegar.

Pediculosis corporis (body lice)

This is rare in children except in severely overcrowded conditions with poor hygiene. The organism infests bedding and clothing and the nits are not found on the human host. The lice hatch with body warmth and puncture the skin, producing very itchy, small, red papules with haemorrhagic puncta. Spots of dried blood may be found on the clothing and bed linen. Treatment is directed towards removal of the organisms from materials with hot water laundering and hot ironing or the use of a hot electric dryer.

Pediculosis pubis (pubic lice, crab lice)

This is mainly an adult disease. The pubic louse has as its normal habitat the anogenital area but in children it is particularly seen on the eyelashes. Eyelash infestation in children may occur from innocent close contact with an affected adult but the possibility of sexual abuse must always be considered. Pediculosis of the eyelashes is best treated with petroleum jelly applied thickly twice a day for a week.

Arthropod bites

Patients with arthropod bites present to a dermatologist in two situations: the severe local allergic reaction and the more chronic hypersensitivity condition called ‘papular urticaria’. The arthropods most encountered are mosquitos, sand flies, fleas and grass mites. The distribution of the bites helps to suggest the causative agent.

Severe local reactions

• Include blisters, purpura and cellulitis and lymphangitis even in the absence of infection

• As the lesions are extremely itchy, scratching occurs, leading to secondary eczematization and secondary infection.

Papular urticaria

• A very common condition in children, particularly between 10 months and 4 years

• In a child who has been sensitized by previous exposure the bite produces an itchy urticarial (hive-like) weal, which is succeeded by a firm itchy papule that lasts for many days

• The weal and papule usually show a central punctum and the papule may be surmounted by a tiny blister

• The persistence and severity of the condition are explained by the fact that new bites by the same species will often cause a recrudescence of activity in resolving lesions

• Secondary infection and eczematization from scratching also contribute to the chronicity of the condition, which may plague the child through an entire summer

• Management involves avoidance of insect attack, with the use of insect repellents, insecticides, protective clothing and changes in activities, which clearly are difficult in an active child. Wrapping the affected areas in wet dressings overnight as soon as new bites occur is helpful in reducing the itch and preventing scratching, which leads to the secondary eczema and infection. Topical corticosteroids will improve the secondary eczema and have some effect in dampening the severity of the actual bite reaction but must not be used for prolonged periods. Oral antibiotics are required if there is significant secondary infection.

Forms of dermatitis

Atopic dermatitis (atopic eczema)

Atopy is a genetically determined disorder with an increased tendency to form IgE antibody to inhalants and foods and increased susceptibility to asthma, allergic rhinitis and atopic eczema (Ch. 13.1). This eczema may begin at any age but 75% of patients show the first signs by 6 months.

Clinical features

The characteristic clinical features are a generalized dryness and a tendency to lichenification or thickening of the skin, pruritus and excoriations and patches of acute, subacute or chronic eczema. Involvement of the whole cutaneous surface may occur but the predominant areas are the face in infants, extensor aspects of the limbs as the child begins to crawl and the limb flexures in older children. In severe cases the whole skin may be erythematous and in these patients white dermographism is often a prominent feature: this indicates that the condition is likely to be unstable and difficult.

Complications

Patients with atopic eczema may develop secondary bacterial infection that presents either as yellow crusting impetigo or folliculitis, or simply as worsening eczema. Mollusca contagiosa are common and atopic patients are at risk of developing severe widespread herpes simplex infections. The usual childhood immunizations are quite safe.

Management

Explanation and education

The most important aspect of the management of atopic eczema is explanation of the condition to the patient or, more commonly, his/her parents. The family should understand that the child has been born with an inherently dry, irritable skin and that this will be a lifelong tendency. While the skin does become more stable with time, it will always require extra care. It is essential to talk in terms of control rather than cure, otherwise the family search for an endpoint after which care will no longer be required and this is an unrealistic expectation. The condition should be explained as a multifactorial disorder as it must be appreciated that, just as there is no ‘cure’, there is no single ‘cause’.

Avoidance of irritants

Factors that will often irritate the atopic skin should be discussed. Woollen material in direct contact with the skin is a major irritant; apart from the child’s own clothing it is important to remember the parent’s clothing, carpets, blankets, stroller and car seat covers, furniture and toys. Shiny nylon materials and some acrylics irritate but cotton–polyester mixtures are usually well tolerated. Sand contact is often troublesome, especially with prolonged close contact as in playing in a sandpit. Chlorinated water may aggravate but this is variable. Soap in excess and bubble baths over-dry the skin, and many perfumed and ‘medicated’ products, disinfectants and strong cleansers cause irritation.

Dealing with dryness

Bath oils and oatmeal-containing products are useful and prevent the defatting of the skin that bathing can induce. It is essential to find a suitable moisturizer that can be applied all over twice a day, whether or not there is active eczema. Glycerine 10% in Sorbolene cream is useful in many cases but more or less greasy preparations are available to suit individual patients and climatic conditions. Urea-containing products sting broken skin and are unsuitable.

Topical corticosteroids

These are an essential part of treatment. In general, ointment bases are preferred because they are more emollient than cream bases. Nothing stronger than 1% hydrocortisone should be used on the face or in the axillae or groin. Medium-strength fluorinated corticosteroids are usually adequate for lesions on the trunk and limbs; the stronger preparations are rarely required. These preparations are best used three times a day and, of course, ceased as soon as the eczema is clear.

Wet dressings

These are useful in severe widespread eczema. A water-based emollient is applied all over; a corticosteroid cream (rather than ointment in this case because cream is more water-miscible) is applied to the areas of active eczema; sheeting soaked in tap water is applied and bandaged on with a crepe bandage and a net material is used to hold the dressings in place. The procedure is repeated three times a day. These dressings cool the skin down, reduce itching, physically prevent scratching, increase the hydration of the skin and enhance the penetration of topical steroids. This treatment is usually effective in clearing the eczema in 3–4 days. If dressings are required for longer periods the corticosteroid should be used only once a day. Particular care should be taken with infants.

Systemic therapy

If significant bacterial infection occurs a swab should be taken and oral antibiotics used. Nocturnal sedation is often valuable during severe episodes but daytime sedation should be avoided; antihistamines are the preferred sedatives. While they may be essential for associated diseases, oral corticosteroids should never be instituted for the eczema itself; a severe rebound can occur on their withdrawal and after several courses the eczema can become very unstable.

Dietary manipulation

No alteration should be made to the patient’s diet unless the atopic eczema has failed to respond to conventional therapy properly carried out. There is only a small group of patients with unstable eczema with an associated urticarial element in whom dietary factors are of major significance; skin prick tests are useful in this group to give a guide for dietary manipulation, which should be instituted only by those with a full understanding of the nutritional requirements of young children.

Dust mite allergy

This is important in a selected group of patients. In these children the eczema is usually particularly troublesome on the face and neck. The family should be given details of dust mite reduction strategies.

Discoid eczema

• In children this is often a manifestation of a combined atopic and psoriatic diathesis

• Well-defined patches of acute eczema occur in a strikingly symmetrical distribution. In infants the commonest sites are the upper back and the tops of the shoulders; in older patients the extensor aspects of the limbs are particularly involved. The lesions may be very thick and exudative and they are very itchy

• Discoid eczema should be distinguished from tinea and impetigo, which are less symmetrical, and classical psoriasis, which is rarely moist

• Management involves emollients and topical steroids as for atopic dermatitis, with the continued use of emollient helping to prevent recurrences.

Pityriasis alba

This condition probably represents a very mild eczema, which, however, produces a striking postinflammatory depigmentation. The condition is more common in atopics, and occasionally some areas will show erythema and more definite eczematous changes:

• appears as poorly defined, slightly scaly, hypopigmented patches occurring particularly on the face and the upper arms

• the mild irritation and signs of mild eczema respond to emollients and weak topical corticosteroids but the hypopigmentation may be very persistent and require sun exposure over a prolonged period before repigmentation is complete

• the condition should be differentiated from vitiligo, where there is total depigmentation and no scale, and from tinea versicolor, which is rare on the face, has very well demarcated lesions and has a very fine branny scale.

Clinical example

Harry, aged 4, presented with a swelling and redness around one eye. It was diagnosed by the ophthalmology registrar as preseptal orbital cellulitis, the child was admitted to hospital and intravenous antibiotics were started. It was remarked that a lack of fever and pain was unusual in a child with cellulitis. The next day the area was more swollen and some blistering had occurred. Harry was noted also to have multiple linear blistered red lesions on his arm. Harry’s mother told the registrar that Harry’s best friend from the preschool had similar lesions on the arms and face, which had been diagnosed by a dermatologist as a plant contact dermatitis. The history obtained was that the preschool garden had been landscaped by parents over the previous weekend and the two children carried Robyn Gordon grevilleas in the car for planting. Harry’s antibiotics were ceased and he was discharged from hospital on a 5-day course of oral steroids. The swelling resolved in 2 days and in 6 days all the rash had disappeared. The following weekend the Robyn Gordon grevilleas were removed from the preschool.

Contact allergic dermatitis from plants (Fig. 21.1.15)

• The commonest causative agents in Australia are rhus and a variety of grevilleas, including Robyn Gordon, Ned Kelly and Hookerana

• The dermatitis is usually very severe and blistering often occurs

• It often occurs in a streaky pattern where the plant has brushed against the skin

• Initially there may be much oedema, especially on the face, and cellulitis is often suspected; however, the child is afebrile and the area is itchy rather than painful

• The condition may be spread beyond areas of initial contact as a result of retention of allergen on clothing and under the nails

• A strong topical steroid may be adequate for localized areas but a short course of oral steroids is usually indicated.

Napkin rashes

Common causes

• Seborrhoeic dermatitis. Presents as a dull red rash covering most of the napkin area, sometimes with a greasy yellow scale, although this is characteristically absent in this moist area

• Monilia. Manifested as a thick, white material deep in the folds and as small annular lesions with an overhanging white macerated scale at their margin

• Irritant dermatitis from urine and faeces. Irritant dermatitis due to urine affects mainly the convex surfaces, with relative sparing of the flexures; irritation due to faeces particularly affects the natal cleft. Napkin dermatitis is rarely caused by irritant or allergic reactions to laundering products

• Miliaria. Sweat duct occlusion may occur alone or in combination with other elements. This presents as small red papules, which are very transient so the pattern varies considerably from hour to hour.

Variants of common types

• Gluteal granulomas. Occur on top of a pre-existing napkin rash as purplish nodules that tend to be oval in shape, following the lines of the skin folds

• Erosive napkin rash. Occurs in the perianal and natal cleft area and usually follows a period of diarrhoea. It is seen in infants with lactose intolerance

• Ulcerated nodules. Most often occur in the vulval area in a situation of a constant urinary leak in the presence of major congenital anomalies

• ‘Frog plaster’ napkin rash. Due to the accumulation of faeces, and to a lesser extent, urine under the plaster used in cases of developmental dysplasia of the hip, and usually of a mixed erosive and ulcerated nodule type.

Other causes

• Psoriasis (Fig. 21.1.16). Produces a bright red, glazed, clearly marginated napkin rash. This may develop into the condition called ‘napkin psoriasis’. A few small scaly spots occur on the trunk above the psoriatic napkin rash, followed by a sudden explosion of typical psoriatic lesions on scalp, face and all over the trunk. The infant is well and the condition is usually asymptomatic. The eruption is self-limiting in a few weeks

• Impetigo. Presents as small, pus-filled blisters that quickly rupture and expand into large superficial erosions, usually asymptomatic

• Herpes simplex. Punched-out 3–8  mm individual erosions that coalesce to form geographical-shaped lesions; considerable swelling is usually seen and there is associated lymphadenopathy and fever

• Staphylococcal scalded skin syndrome. May present in the napkin area with a very painful bright red rash with superficial blistering

• Kawasaki disease. Often presents in the napkin area with a tender red scaly rash in a febrile child

• Langerhans cell histiocytosis. Produces a severe napkin rash with a brownish scale, erosions and purpuric spots

• Zinc deficiency. Produces a well marginated shiny rash rather similar to psoriasis, but with a characteristic dark peripheral scale. Similar lesions are present around the mouth and nose.

Psoriasis

Psoriasis is a hereditary disease: it is probably an autosomal dominant condition with variable penetrance. It commences by the age of 15 years in 30% of patients. It may present in the typical adult form of large erythematous plaques, with a thick, silvery white scale, predominantly on the knees, elbows, buttocks and scalp, but certain differences are seen in childhood disease:

• plaques are usually smaller and with a finer scale (Fig. 21.1.17)

• a particularly common presentation is acute guttate psoriasis with the eruption of tiny papules in a widespread distribution. The eruption is often preceded by an intercurrent illness, particularly a streptococcal throat infection

• the face and intertriginous sites are commonly affected in children

• children presenting with vulvitis, balanitis and perianal itching may be found to have psoriasis. In these areas the typical scale is absent and the condition presents as a glazed erythema, often with fissuring

• nail involvement is usually absent or minimal with minor pitting

• pustular psoriasis and psoriatic arthropathy are extremely rare in children

• there is a particular type of well marginated, bright red napkin rash, described above, that is a marker for psoriasis

• many therapies used in adults are inappropriate in children. In general, psoriasis in children is better treated with tars than topical corticosteroids. No treatment can alter the course of the condition.

Photosensitivity

Photosensitivity may be manifested by exaggerated sunburn or another rash appearing in a light exposed area. There are many causes and some are briefly reviewed here:

• Phytophotodermatitis – contact with a phototoxic agent (e.g. lime juice, perfumes) followed by sun exposure causes an exaggerated sunburn reaction

• Drug reactions – rare in children

• Polymorphous light reaction – may produce recurring erythematous, itchy vesicles and papules on the cheeks, ears, side of the neck and exposed limbs. The onset of the eruption may be delayed 1–2 days after sun exposure, but the distribution of the lesions and history of exacerbation in the summer months are typical

• Solar urticaria – a very transient urticarial rash appearing immediately after sun exposure

• Connective tissue diseases

• lupus erythematosus

• dermatomyositis

• Porphyrias

• erythropoietic protoporphyria

• congenital erythropoietic porphyria

• Other genetic disorders leading to increased sun sensitivity

• albinism

• xeroderma pigmentosum

• Bloom syndrome

• Rothmund–Thomson syndrome.

Hair loss in children

There are two major types of hair loss (alopecia): diffuse and patchy. The commonest cause of localized alopecia is telogen effluvium and the main causes of patchy alopecia are tinea, alopecia areata and trichotillomania.

Diffuse alopecia

• Telogen effluvium – high fever causes a large number of hairs to enter the resting or telogen stage of the hair cycle prematurely; 2–3 months later these inevitably fall. The hairs have a club-shaped end visible as a white dot with the naked eye. New hairs immediately appear in the empty follicles. The condition may continue for several months but is fully reversible.

• Some other causes are:

• drugs

• malnutrition

• iron deficiency

• various aminoacidurias

• hereditary hair shaft abnormality syndromes

• congenital atrichia

• 

alopecia as a part of other genetic syndromes.

Patchy alopecia

• Tinea – combination of inflammation of varying degree and broken hairs

• Alopecia areata – autoimmune disease with areas of total hair loss and no obvious inflammation; there may be some short, so-called ‘exclamation mark hairs’ at the edges

• Trichotillomania – hair twisting or plucking. Hairs broken at different lengths, usually no inflammation

• Some other causes:

• 

hair cutting as a form of artifactual skin disease

• traction: from tight hair styles

• 

infections: boils, erysipelas, herpes simplex, herpes zoster, tick bites

• localized scleroderma.

Practical points

• A haemangioma in a beard distribution can be a marker for subglottic haemangioma

• Haemangiomas usually appear after birth, always grow out of proportion to the growth of the child and always undergo resolution

• Vascular malformations are always present at birth, grow only in proportion to the child’s growth and never resolve

• Herpes simplex lesions are grouped and tend to coalesce forming geographical-shaped erosions

• Painful defaecation, bright blood on the stool and a bright red rash in the immediate perianal area point to streptococcal perianal infection

• The combination of broken hairs and inflammation suggests tinea capitis

• Scabies nodules can persist for months after effective scabies treatment

• Apparent cellulitis that is itchy, occurs in a well, afebrile child and begins on the second day to blister suggests allergic contact dermatitis to a plant

• A bright red, well marginated napkin rash suggests psoriasis

21.2

Systemic implications of skin disease in children

R. Phillips

Virtually all systemic diseases lead to skin changes sooner or later. Conversely, many skin conditions have the potential to cause dysfunction in other body systems. This chapter focuses on skin changes in children that require examination and/or investigation for systemic problems. The systemic problem may be the cause of the rash, or it may be caused by the skin disease.

In this chapter, we discuss the significance of different morphological types of rash in turn, namely vesicles and pustules, ulcers, papules, scaly rashes, eczematous rashes, erythematous rashes and purpuric rashes. Vascular and other birthmarks, pigmentary changes, anogenital rashes, skin texture and hair are considered separately.

Practical points

• Many diseases can present with a rash as the first sign

• Widespread chronic eczema is usually associated with systemic complications including psychosocial and growth problems

• Chronic generalized skin disease from any cause is often associated with morbidity in growth and nutrition

• Beware of a common rash presenting in an unusual way, such as early-onset acne

• Drug reactions are common. Most drugs used for systemic disease can cause a rash and most drugs used for skin disease can cause systemic disease

• Purpuric rashes require immediate assessment to exclude life-threatening conditions such as meningococcal disease

Vesicular, bullous or pustular rashes

Vesicles and pustules are considered together in this section as there is substantial clinical overlap. Vesicles from any cause usually become pustular in a couple of days if they have not ruptured.

In the neonatal period, pustules may be part of several transient dermatological conditions (Ch. 21.1) but pustules or vesicles may also be a marker of serious underlying illness, even in the absence of fever and lethargy. Consider:

• infection, either congenital or acquired. Herpes simplex virus (Ch. 21.1), varicella, Listeria, Staphylococcus, Streptococcus, Haemophilus, Neisseria or Candida species may be present

• neutropenia from any cause. Superficial bacterial pustules may be the only sign of congenital neutropenia

• incontinentia pigmenti. This disease is X-linked and fatal in male fetuses. Girls present with lesions distributed in linear patterns following the lines of Blaschko (not dermatomal lines; Fig. 21.2.1). Lesions evolve through vesicular and warty phases to eventually leave permanent hyperpigmented streaks. Seizures and developmental, ocular and dental problems may occur (Fig. 21.2.2).

At any age, consider:

• Langerhans cell histiocytosis

• drug reactions. These can manifest as phototoxic or photosensitive reactions (Ch. 21.1) or bullous drug reactions. Stevens–Johnson syndrome presents with mucocutaneous erosions and blistering in association with erythematous or purpuric macules, lethargy, fever, lymphadenopathy and conjunctivitis, occasionally leading to death or blindness. Most cases are secondary to medications, often non-steroidal anti-inflammatory drugs

• dermatitis herpetiformis. This may present in older children as itchy papules or vesicles, often on extensor surfaces. Most patients have gluten enteropathy (coeliac disease) and may have abdominal discomfort, diarrhoea or anaemia.

Acneiform rashes

Some degree of acne is occasionally seen on the face in infancy and is common on the face and upper trunk during puberty. Comedonal acne may be the first sign of puberty. Acne, particularly if severe, can lead to significant depression in adolescents and is a risk factor for suicide. Both the depression and the acne need to be recognized and treated. Acne that is atypical in age of onset, distribution, morphology or severity may be associated with systemic disease. Consider:

• glucocorticoid excess, either exogenous or endogenous. This can give a monomorphic acneiform rash on the face and trunk. Other cushingoid stigmata are usually present

• androgen excess. Look for accelerated growth, body odour, pubic hair, clitoromegaly (but not breast development) and penile (but not testicular) enlargement (Fig. 21.2.3). In teenage females, polycystic ovary syndrome is commonly the cause

• precocious puberty

• medications. In postpubertal children, antiepileptic medications, especially phenytoin and phenobarbital, may induce acne

• tuberosclerosis. Facial angiofibromas may be the first sign of tuberosclerosis and may be misdiagnosed initially as acne or plane warts.

Chronic erosions or ulcers

Any itchy condition such as scabies or papular urticaria can lead to chronic erosions via persistent scratching. Several primary skin conditions can cause chronic erosions or ulcers in children. Consider:

• immunodeficiencies. Recurrent boils can be seen in chronic granulomatous disease and hyper IgE syndrome. Poor wound healing is a feature of leukocyte adhesion defects

• skin fragility syndromes. In junctional and dystrophic forms of epidermolysis bullosa, chronic ulcers related to minimal skin trauma may be seen in association with failure to thrive, anaemia and gastrointestinal tract involvement

• porphyria. Several enzyme defects in haem metabolism are associated with chronic erosive lesions, photosensitivity and hyperpigmentation. Episodes of acute pain or neurological dysfunction are rarely seen in childhood porphyrias.

Recurrent mouth ulcers

These are generally due to aphthous stomatitis. Such ulcers are usually small and resolve in a few days. Recurrent mouth ulcers can also be seen in:

• iron, folate or vitamin B12 deficiency

• gastrointestinal disorders. Coeliac disease, Crohn disease and ulcerative colitis are all associated with mouth ulceration. Recurrent abdominal pain, intermittent diarrhoea and failure to thrive may be present

• connective tissue disorders. Patients with Behçet disease usually present in late childhood with ulcers at one site (mouth or genitals) and it may be many years before a second site is involved. Systemic lupus erythematosus and juvenile rheumatoid arthritis may cause recurrent mouth ulcers

• immunodeficiency states, human immunodeficiency virus (HIV) infection

• malignancy. Lymphoma and histiocytosis can present with non-healing mouth ulcers.

Papular rashes

Papules or nodules may occur in a number of disorders, including acute rheumatic fever, juvenile chronic arthritis, systemic lupus erythematosus and neurofibromatosis, but are rarely the presenting feature. Erythematous papules, often itchy, scaly or purpuric, may be widespread in acute Langerhans cell histiocytosis. Severe, recalcitrant ‘cradle cap’ or weeping intertriginous lesions may also be present, along with single or multiple bone lesions, mucosal ulceration and involvement of other organs. In neonates, Langerhans cell histiocytosis may present as a few nodules, classically with a raised border and central necrosis. This congenital self-healing form usually shows complete regression within months but visceral involvement may occur. Local or generalized disorders of parathyroid or calcium metabolism can present as calcified or ossified papules (Fig. 21.2.4).

In children, yellow papules are commonly xanthogranulomas. The yellow colour is best seen by pressing over the papule to blanch the overlying capillaries. Xanthogranulomas are often isolated lesions that resolve within a few years. They are not associated with lipid disorders. By contrast, multiple eruptive xanthomas, tuberous xanthomas (usually distributed over the elbows, knuckles, buttocks, knees and heels) and tendinous xanthomas (usually on tendons around the elbow, wrist, hand or ankle) are associated with elevated cholesterol levels. Consider:

• primary hyperlipoproteinaemias. Skin lesions may present between 5 and 15 years of age, sometimes as tendinitis or tenosynovitis. Look for signs of atherosclerotic disease and a family history of high cholesterol, early myocardial infarcts or strokes

• secondary hypercholesterolaemia. This can occur in hypothyroidism, biliary cirrhosis, diabetes mellitus, glycogen storage disease and nephrotic syndrome.

Scaly rashes

Ichthyosis refers to generalized scaly skin. Some ichthyoses only affect the skin but several involve other organs:

• X-linked ichthyosis is quite common but may be undiagnosed. A fine scaling at birth is later replaced by larger, brown scales. Diagnosis is confirmed by leukocyte enzyme analysis. Boys with X-linked ichthyosis need to be monitored for hypogonadism, cryptorchidism, anosmia, short stature and mental retardation. Female carriers may have obstetric difficulties

• in Sjögren–Larsson syndrome, a yellow-brown lichenified appearance is present in infancy. This evolves into a more florid scaling with a symmetric spastic paralysis and mental retardation

• in some trichothiodystrophies, ichthyosis is associated with brittle hair and mental and growth retardation

• several ichthyoses are linked with deafness, cataracts or other eye problems. Mild, generalized scaling may be the first feature in later-onset Refsum disease, before development of multiple visual problems, deafness and neuropathy.

Ectodermal dysplasias are a heterogeneous group of conditions characterized by congenital, non-progressive abnormalities of hair, teeth, nails and sweat glands. The skin is dry and may be hyperpigmented. Deficient sweating may cause overheating in summer. Teeth are often poorly developed or absent. Cleft lip and palate, limb abnormalities and mucous retention in the upper airway and ear may be present.

Clinical example

A 2-year-old boy attended because he had twice collapsed on hot days over summer. Examination revealed dry skin with sparse hair and deficient dental development. His nails were somewhat hypoplastic. This story is suggestive of ectodermal dysplasia, probably X-linked. History and examination confirmed the near-total absence of sweating. He was at risk of overheating and his family needed to be counselled about strategies to prevent this. Siblings and other family members should be examined and genetic counselling provided.

Eczematous rashes

Atopic eczema is common and in most cases can be readily controlled with minimal sequelae (Ch. 21.1). However, a few children have chronic and severe disease requiring frequent, time-consuming applications of topical medicines and wet dressings. These children may have recurrent infections, particularly with Staphylococcus aureus and herpes simplex virus. There may be failure to thrive. Severe psychosocial, behavioural and marital problems are common in these severely affected children, although often hidden from medical staff. These problems need to be identified and addressed.

Eczematous skin lesions can also be associated with:

• immunodeficiency syndromes. Thrombocytopenia, immunodeficiency and eczema are seen in Wiskott–Aldrich syndrome. Failure to thrive, petechiae, recurrent infections, diarrhoea or haematological abnormalities may suggest this or other immunodeficiencies that are variably associated with eczema

• multiple food allergies with consequent dietary restrictions and secondary nutritional and psychosocial problems

• metabolic or nutritional disorders. Phenylketonuria often presents with eczema. Less typical eczematous lesions, more prominent in periorificial areas, are seen in biotin, essential fatty acid and zinc deficiency syndromes. Malnutrition and organoacidaemias, e.g. methylmalonicacidaemia, can result in similar lesions.

Erythematous (red blanching) rashes

Neonatal erythroderma

Erythroderma (inflammation of almost all the skin surface) in the neonatal period requires close monitoring and early investigation to identify the underlying cause. Eczema rarely presents as erythroderma. Exclude staphylococcal-toxin-mediated infections and congenital candidiasis. Metabolic causes include inherited carboxylase deficiencies and essential fatty acid deficiency secondary to any severe malabsorption, and can be associated with severe acidosis and coma. Omenn syndrome (familial reticuloendotheliosis with eosinophilia), maternal graft-versus-host disease and other severe immunodeficiencies can present as erythroderma. Drug reactions are an unlikely cause at this age. Some variants of ichthyosis can present as erythroderma and may be associated with multiple infections, failure to thrive or cataracts.

Annular rashes

Annular lesions are ring-shaped with relatively normal skin centrally. Such lesions are typical of tinea corporis, urticaria and granuloma annulare but may require investigation for neonatal lupus (caused by transfer of maternal antinuclear antibodies across the placenta; look for heart block and maternal antinuclear antibodies), rheumatic fever, syphilis and Lyme disease.

Clinical example

A 4-week-old baby presented with multiple red scaly rings on her face and trunk. These had been treated as eczema with hydrocortisone, without response. A trial of clotrimazole cream for tinea corporis was also ineffective. Upon questioning, the mother remarked that the 8-year-old brother had also developed a persistent annular rash as an infant. Testing the mother confirmed the presence of antinuclear antibodies, consistent with a diagnosis of neonatal lupus in the two children. Neither sibling had congenital heart block. The mother remains clinically normal.

Erythema nodosum

Erythema nodosum can occur at any age and presents initially as subcutaneous erythematous lesions mainly on the anterior lower legs. They may progress to extensive bruise-like lesions. Erythema nodosum may be idiopathic or associated with chronic streptococcal disease, pulmonary or other tuberculosis, Crohn disease, chronic gastrointestinal infections, sarcoidosis and Mycoplasma infection. It may also be secondary to a number of drugs.

Urticaria

Urticaria describes circular erythematous macules or swellings, often with central pallor, that appear, migrate and disappear over minutes or hours. It is common. Usually no cause is found but recurrent or chronic urticaria may be related to underlying inflammatory conditions such as systemic lupus erythematosus, juvenile chronic arthritis, other vasculitic diseases and parasitic infection. In a child who is very unwell, consider Kawasaki disease.

Generalized erythematous rashes

Erythematous rashes with fever are common in children. Many widespread childhood viruses may be accompanied by an erythematous rash. Occasionally the clinical pattern is distinctive and a confident diagnosis can be made. Usually the diagnosis cannot be made clinically. If the diagnosis is not clear, decide if the child is significantly unwell. Any signs of decreased responsiveness, lethargy or shock may require urgent investigation for causes such as septicaemia and Kawasaki disease. In otherwise well children, consider whether the rash may be a drug reaction. If any relatives may be at risk (e.g. immunosuppressed siblings, pregnant women), serological and virological testing to identify a cause may be appropriate. Usually, no investigation is needed:

• the skin lesions of systemic lupus erythematosus include a characteristic butterfly distribution over both cheeks and the base of the nose. Patchy lesions may also present over the ears, neck and less commonly the limbs. In acute systemic lupus erythematosus, erythematous macules are also seen about the nail beds, on the tips of the fingers, the toes, and on the palms of the hands and soles of the feet

• an erythematous maculopapular rash is often seen in the systemic form of juvenile chronic arthritis. This rash usually has a salmon pink colour and tends to come and go, being particularly evident at the time when the fever is at its height. It may be urticarial

• the lesions of Henoch–Schönlein purpura may be erythematous and urticarial rather than purpuric

• an erythematous rash that is distributed over the extensor surfaces of the joints, particularly over the knuckles, elbows and knees, is characteristic of dermatomyositis. In addition, most children with this disorder show a violaceous facial rash and periorbital oedema

• an erythematous rash accompanied by oedema of the palms and soles is often prominent in Kawasaki disease. Other early features include prolonged high fever, conjunctivitis, redness, swelling or ulceration of mucosal surfaces and enlargement of lymph nodes. Desquamation of the hands and feet is a later finding.

Purpuric rashes

Most children presenting with fever and petechiae (pinpoint purpura) but who are otherwise well have an enteroviral infection without other findings. However, purpuric rashes are associated with several life-threatening diseases. They require urgent assessment.

Neonatal purpura

Purpuric rashes in the neonatal period may be an early presentation of any cause of childhood purpura (see below). In addition, consider:

• congenital infection, including rubella, cytomegalovirus, toxoplasmosis, and herpes simplex

• haemolytic disease of the newborn

• malignancy, including neuroblastoma, Langerhans cell histiocytosis and leukaemia

• iatrogenic injury, including birth trauma, extravasation of drugs and arterial injury during catheterization.

Childhood purpura

Purpuric rashes in childhood are usually secondary to vascular dysfunction rather than a low platelet count. Consider:

• septicaemia. An unwell febrile child with purpura should be treated for meningococcal septicaemia without waiting for the results of investigations. Septicaemia from Haemophilus influenzae, streptococci, staphylococci and some Gram-negative organisms may cause purpura. Less extensive, but diagnostically useful, are the purpuric lesions of subacute bacterial endocarditis, typhus and typhoid fever. Purpura may also occur in certain viral haemorrhagic fevers

• coagulation disorders. There may be a history of joint pain or swelling, or bleeding from other sites

• Henoch–Schönlein purpura. This is quite common in childhood. Purpuric lesions on the legs and buttocks may be the only finding in Henoch–Schönlein purpura or there may be associated abdominal pain, arthritis or renal involvement. Children with Henoch–Schönlein purpura should be monitored for months for the development of nephritis

• other vasculitic diseases

• Langerhans cell histiocytosis (Fig. 21.2.5)

• glucocorticoid excess

• any cause of abnormal skin elasticity

• scurvy. Irritability, bone pain, gum sponginess and bleeding may be present. Wrist X-rays are diagnostic

• child abuse. Bruises of different ages and at unusual sites may be seen

• trauma.

Childhood purpura with thrombocytopenia

Purpura in association with a low platelet count is often associated with bruising and signs of bleeding elsewhere. Idiopathic thrombocytopenic purpura is the most common cause. Children need to be examined and investigated for leukaemia, pancytopenia, splenomegaly and drug-induced thrombocytopenia or aplastic anaemia (chloramphenicol, antithyroid medications).

Haemangiomas and vascular malformations

Haemangiomas and vascular malformations are discussed in Chapter 21.1. They are often isolated lesions but may be part of systemic disease. Consider:

• ocular involvement. Children with any vascular lesion around the eye should be screened for glaucoma and other eye abnormalities. Children with haemangiomas adjacent to the eye may develop amblyopia (blindness) secondary to the visual axis being obstructed or secondary to astigmatism caused by pressure of the tumour on the globe

• intracranial involvement. Children with capillary malformations involving the region of the first division of the trigeminal nerve may also have intracranial involvement and develop epilepsy, strokes, hemiplegia or mental retardation (Sturge–Weber syndrome)

• occult spinal abnormalities

• intestinal lesions. Multiple cutaneous and visceral vascular lesions occur in blue rubber bleb syndrome and may cause intestinal bleeding. Telangiectases in hereditary haemorrhagic telangiectasia usually appear on the face, mouth and nose. Nose bleeds become frequent in late childhood and gastrointestinal bleeding occurs in adult life

• overgrowth syndromes. Extensive vascular malformations can be associated with limb overgrowth and other organ involvement in Klippel–Trénauney and Proteus syndromes

• cutis marmorata telangiectatica congenita. Reticulated, vascular lesions on the skin may be associated with asymmetric limb growth (sometimes distant from the skin involvement) and glaucoma

• coagulopathy (Kasabach–Merritt syndrome). This occurs with rare subtypes of haemangioma. Rapid enlargement of the haemangioma accompanies purpura and bleeding, thrombocytopenia and disseminated intravascular coagulation

• Fabry disease. Angiokeratomas (flat or raised, slightly warty, telangiectatic or vascular lesions) appear on the lower trunk, pelvis and thighs. There may be limb pain or paraesthesia, or corneal opacities. Renal, cardiac and central nervous system problems occur later

• fucosidosis. Severely affected children die early. In mild cases, children may present with angiokeratomas and anhidrosis in later childhood. Look for coarse facies, developmental delay and growth retardation

• telangiectasia ataxia. Some degree of ataxia is usually present by the time conjunctival telangiectases are noted.

Lumbosacral birthmarks

Congenital lesions over the lumbosacral area may be associated with occult spinal abnormalities such as a tethered cord. These spinal anomalies may not cause problems until later in childhood when they can present insidiously with irreversible bladder, bowel or limb dysfunction. These problems can be prevented by early magnetic resonance imaging (MRI) screening and surgical correction. Congenital lesions that have been associated with underlying spinal problems include haemangiomas, capillary malformations, lipomas, dimples, sinuses and hairy patches.

Hypopigmented lesions

Generalized hypopigmentation

Generalized hypopigmentation, blonde hair and grey-blue eyes are seen in several genodermatoses involving chromosomes 11 or 15. The clinical presentations vary from mild to complete loss of pigmentation and individuals may go undiagnosed unless compared to their siblings and parents. Early diagnosis and investigation is important to ensure early ophthalmological intervention and rigorous sun protection. Look for:

• poor vision, photophobia and nystagmus. Type 1 oculocutaneous albinism usually results in more severe disease than type 2

• bleeding diathesis, due to a platelet defect in Hermansky–Pudlak syndrome

• recurrent infections in Chédiak–Higashi syndrome

• mental retardation, obesity. Both Angelman and Prader–Willi syndromes can present with albinism.

Localized hypopigmentation

Localized patches of hypopigmented skin or hair may be due to piebaldism, pityriasis versicolor (usually in adolescence), pityriasis alba (usually in mid-childhood), previous inflammation and vitiligo. Also consider:

• endocrinopathies. Vitiligo in children is weakly associated with other endocrine conditions. Children with vitiligo should be reviewed for features of diabetes and thyroid dysfunction

• tuberosclerosis. Hypopigmented patches may be the first sign of tuberosclerosis. These patches can be regular or irregular in shape. An isolated hypopigmented patch in a young child is far more likely to be a simple achromic naevus than to be part of tuberosclerosis, but multiple hypopigmented patches increase the likelihood of tuberosclerosis. Look also for forehead plaques (pink, initially flat but later slightly raised) and shagreen patches (rough, slightly thickened skin, usually over the back). Other skin findings such as periungual fibromas and facial angiofibromas usually appear in older children. The diagnosis of tuberosclerosis may require imaging of eyes, brain, heart and kidneys and investigation of relatives

• streaks, lines and whorls of hyper- or hypopigmentation that may be present from birth. These patterns reflect mosaicism. Usually these children are otherwise normal but a wide range of associated abnormalities in other systems have been reported. Apart from audiological and ophthalmological examination, investigations are not required unless suggested by clinical findings, but these children should be reviewed until settled in school to assess whether any developmental difficulties are present

• leprosy. Focal pale patches may be the only marker of leprosy in an individual from an endemic area.

Hyperpigmented lesions

Generalized hyperpigmentation or skin colour

Generalized darkening of the skin is often most obvious on the palmar creases, linea alba and areola. It is uncommon in childhood. Consider:

• endocrine disease. Addison disease, Cushing syndrome of pituitary origin, exogenous adrenocorticotrophic hormone (ACTH) administration and acromegaly can all cause hyperpigmentation

• renal failure may cause greying of the skin

• haemochromatosis. In children, this is usually secondary to transfusions

• photosensitivity

• lipoidoses. A yellow-brown darkening of skin, most prominent in sun exposed areas, can occur in the Niemann–Pick diseases. Look for waxy indurated skin, purpura, hepatosplenomegaly and neurological deterioration. Although a similar colour can be seen in adult-onset Gaucher disease, it is not a feature of the earlier-onset forms.

Localized hyperpigmentation

Many normal children have one or two well-defined pigmented macules, generally not present at birth but appearing in the early years. In a child with pigmented macular lesions, consider:

• neurofibromatosis. Five or more café au lait spots greater than 0.5  cm in diameter are strong evidence for neurofibromatosis. Examine for other features (axillary ‘freckling’, pigmented or thickened skin over plexiform neurofibromas, iris pigmentation, optic tumours, skeletal abnormalities, short stature, skin neurofibromas, macrocephaly and learning difficulties). The diagnosis may be uncertain early in life. Regular follow-up is needed, including assessment of intellectual progress. Apart from audiological and ophthalmological examination, investigations are not required unless suggested by clinical findings

• McCune–Albright syndrome. Macules are often large and may stop at the midline. Look for fibrous dysplasia, sexual precocity and mental retardation

• incontinentia pigmenti. Hyperpigmented streaks may be the presenting feature if the early vesicular/warty phases occurred in utero or were undiagnosed in infancy and then forgotten

• Peutz–Jeghers syndrome. Small pigmented macules present on the lips and mucosa from birth are associated with intestinal polyposis. Care must be taken when assessing any episodes of abdominal pain in these children as they are at higher risk of intussusception and collapse

• naevoid hyperpigmentation (see Localized hypopigmentation, above)

• pellagra. Hyperpigmentation and erythema on sun-exposed areas, cheilitis, perineal inflammation and diarrhoea may be seen.

If areas of hyperpigmentation are roughened, raised, depressed or warty, consider:

• congenital pigmented naevi. Depending on their site and size, infants with congenital pigmented naevi over the posterior scalp or spine may require imaging to look for meningeal involvement, obstructive hydrocephalus, cerebellar malformation or tethered cord

• genodermatoses such as dyskeratosis congenita. Congenital nail dystrophy, pancytopenia, skeletal and eye anomalies may be present

• necrobiosis lipoidica. Atrophic pigmented patches on the lower legs may be the first sign of diabetes in childhood

• acanthosis nigricans. Rough ‘dirty’ skin on the neck or axillary folds is usually associated with obesity and/or the polycystic ovary syndrome but consider other insulin-resistance syndromes and hypothyroidism. Look for menstrual irregularities and obstructive sleep apnoea. Consider investigation, including liver enzymes and a fasting insulin level to assess for incipient diabetes. If abnormal, perform a formal glucose tolerance test and consider weight-loss strategies and, especially if menstrual irregularities are present, metformin.

Skin texture

Lax, hyperextensible skin is seen in Ehlers–Danlos syndrome. There may be bruising, scarring at sites of minor trauma, joint hyperextensibility and arthritis, and recurrent urinary infections.

Unusually firm skin is an early feature of systemic sclerosis. In children, there is usually widespread skin involvement. Raynaud’s phenomenon may be present, and involvement of lungs, heart, kidneys and gastrointestinal tract usually occurs within a few years.

Waxy indurated skin may accompany neurological degeneration and hepatosplenomegaly in type A Niemann–Pick disease.

Anogenital rashes

Common causes of anogenital rashes include irritant napkin dermatitis, seborrhoeic dermatitis and yeast infection. These usually settle rapidly with treatment. More resistant rashes may be due to psoriasis or perianal streptococcal infection, but also consider:

• Langerhans cell histiocytosis. This may present in infancy as a chronic inguinal rash, often erosive and unresponsive to treatment. A scaly, papular eruption on the scalp or trunk may appear (Fig. 21.2.5). Petechiae, purpura, fever, diarrhoea or hepatosplenomegaly may be present

• nutritional deficiencies. Anogenital lesions are an early and prominent manifestation of zinc deficiency. Look for perioral and acral rashes, alopecia, diarrhoea and failure to thrive. Serum zinc levels do not correlate well with body zinc status. Biotin and essential fatty acid deficiency syndromes can give a similar picture

• malabsorption. Both an intractable irritant napkin dermatitis and secondary nutritional deficiencies may contribute to anogenital rashes in malabsorptive conditions

• congenital syphilis. Perianal erosions and moist warty lesions may be seen in early infancy, with erythema on the palms and soles, fever, failure to thrive and hepatosplenomegaly

• HIV can present as severe, erosive napkin dermatitis, which may be secondarily infected

• family factors. Irritant or traumatic anogenital rashes may be seen in circumstances of suboptimal care, emotional abuse or physical abuse.

Hair problems

Hair loss

See Chapter 21.1.

Hypertrichosis

Generalized hypertrichosis (increased hair in all areas) may be an isolated finding or may be related to:

• inherited syndromes, including Hurler and De Lange syndromes

• medications, especially minoxidil, phenytoin and ciclosporin

• gastrointestinal disease, including coeliac disease

• hypothyroidism

• porphyria; look for photosensitivity and blisters.

Hirsutism

Increased pubic or axillary hair in young children may be due to adrenal, gonadal or central nervous system disease and requires investigation. Hirsutism in adolescent females may be an isolated finding or may be seen with obesity and amenorrhea in polycystic ovary syndrome. Cushing syndrome, mild congenital adrenal hyperplasia, virilizing adrenal and ovarian tumours and thyroid dysfunction may cause hirsutism.

Fig. 21.1.1 Transient neonatal pustulosis.

Fig. 21.1.2 Neonate with congenital ichthyosis covered in tight, thick, red membrane.

Fig. 21.1.3 Congenital melanocytic naevus in ‘garment’ distribution on the back.

Fig. 21.1.4 Epidermal naevi.

Fig. 21.1.5 Superficial haemangioma.

Fig. 21.1.6 Deep haemangioma presenting as bluish tumour.

Fig. 21.1.7 Combined superficial and deep haemangioma.

Fig. 21.1.8 Capillary malformation on the face, involving the brow, which suggests the possibility of the Sturge–Weber syndrome.

Fig. 21.1.9 Herpes simplex on a finger, presenting as intact pustules.

Fig. 21.1.10 Disseminated herpes simplex in a child with atopic dermatitis.

Fig. 21.1.11 Bullous impetigo in a neonate.

Fig. 21.1.12 Staphylococcal scalded skin syndrome in a neonate.

Fig. 21.1.13 Annular lesions of tinea.

Fig. 21.1.14 Scabies nodules.

Fig. 21.1.15 Acute vesicular plant contact dermatitis.

Fig. 21.1.16 Psoriatic napkin rash with early dissemination.

Fig. 21.1.17 Small plaque psoriasis leaving a striking hypopigmentation.

Fig. 21.2.1 Lines of Blaschko.

Fig. 21.2.2 Widespread vesicles in a 6-day-old girl. Recognizing the streaky blaschkoid patterns of the vesicles on the back leads to the diagnosis of incontinentia pigmenti.

Fig. 21.2.3 Comedones and papules on the back of a 6-year-old boy. He was within normal limits for height but crossing centiles upward. Examination was otherwise normal. He requires investigation for androgen excess.

Fig. 21.2.4 These small, rock hard papules were present for several months behind the knee and at two other sites on the trunk of a 1-year-old girl with mild developmental delay. In conjunction with her short fourth metacarpal bones, a diagnosis of pseudohypoparathyroidism was made.

Fig. 21.2.5 This 3-month-old girl was being treated for eczema. However, the distribution and morphology of the chronic rash were unusual. Some lesions were purpuric, suggesting the correct diagnosis of Langerhans cell histiocytosis.

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