I
PATHOLOGY OF THE MOUTH AND SALIVARY GLANDS
Lecture Objectives
At the end of the lecture, the student should be able to:
1. Outline the causes of the main inflammatory lesions of the mouth and pharynx – stomatitis, pharyngitis and tonsillitis.
2. Discuss the pathologic features of benign and malignant epithelial tumours of the mouth.
3. Describe the premalignant epithelial lesions of the oral cavity.
4. List other/non-epithelial tumours that can involve the mouth.
5. Outline the causes of inflammation of the salivary glands (sialadenitis)
6. Name the main benign & malignant tumours of the salivary glands and discuss the pathology of each.
PATHOLOGY OF THE MOUTH AND PHARYNX
1) Inflammation
◆ Stomatitis
➢ This refers to generalized inflammation of the oral mucosa
➢ A variety of lesion types may be seen including vesicobullous lesions (VB) and ulcers (U). Some agents e.g. Candida sp. produce characteristic lesions.
CAUSES OF STOMATITIS
|Class of agent |Example |Type of lesion |
|Virus |Herpes simplex |VB/U |
| |Varicella |VB/U |
| |Coxsackie, type A |VB/U |
|Fungus |Candida albicans |Thrush/U |
|Bacteria |Vincent’s disease |U |
|Autoimmune |Pemphigus |VB |
| |Bullous pemphigoid |VB |
| |SLE |U |
|Other/unknown |Erythema multiforme |VB |
| |Lichen planus |U |
| |Aphthous stomatitis |U |
❑ Candidiasis
➢ Usually attributable to infection with C. albicans but other species can be causative
➢ Risk factors include immunosuppression, altered oral microflora (e.g. broad-spectrum antibiotics), denture use and endocrine disorders e.g. poorly controlled diabetes mellitus
➢ There are numerous manifestations of oral candidiasis and some of the main ones are outlined:
Thrush: “pseudomembranous candidiasis”—loosely adherent white pseudomembrane (fungi,
inflammatory cells, debris, fibrin and bacteria) overlies inflamed mucosa
Angular stomatitis: infection in deep grooves of the lips
Candidal leukoplakia: tightly adherent membrane—?associated with heavy cigarette smoking
Chronic mucocutaneous candidiasis: skin, nails and other mucous membranes involved; many variants including familial, sporadic and those assoc. with various endocrine and chronic disorders
❑ Vincent’s disease (Acute necrotizing ulcerative gingivitis)
➢ Incompletely understood but factors such as emotional stress and smoking may suppress immune system and predispose to infection by commensal organisms such as Bacteroides sp.
➢ Characterized by gingival necrosis, ulceration and pseudomembrane formation
❑ Aphthous stomatitis ( Recurrent aphthous ulcers)
➢ Condition characterized by recurrent shallow ulcers (aphthae); may be single or multiple
➢ 10 to 20% of individuals affected—the most common disease of the oral mucosa; women>men; 10 to 30 yr.
➢ Seen in healthy people; occasionally assoc. with certain diseases e.g. Crohn’s
➢ Cause still unknown—? Trauma/stress/food products/nutritional deficiency/hormones
➢ Aphthae last 1 to 3 weeks, subsequent episodes vary in frequency and the condition eventually spontaneously disappears in most people
( Acquired immunodeficiency syndrome
➢ Oral lesions are prominent, often early features in HIV-related diseases
➢ Refractory candidiasis e.g. thrush is often the first manifestation
➢ Specific oral lesion of HIV is hairy leukoplakia—bilateral, soft, white, hairy excrescences on the lateral margins of the tongue: squamous hyperplasia that appears to be induced by EBV ? in assoc. with Candida or HPV.
Oral Manifestations of AIDS
|Secondary infections | |
|Fungal |Candidiasis |
| |Histoplasmosis |
| |Cryptococcosis |
|Bacterial |Increased risk of dental caries and periodontitis |
| |Acute necrotizing ulcerative gingivitis |
| |Mycobacterial infection |
| |(such as M. tuberculosis, M. avium-intracellulare) |
| |Gram-negative bacteria (such as Klebsiella pneumoniae) |
|Viral |Herpetic stomatitis |
| |Cytomegalovirus |
| |Hairy leukoplakia |
| |Herpes zoster |
| |HPV (condyloma acuminatum) |
|Tumours |Kaposi’s sarcoma |
| |Squamous cell carcinoma |
| |Non-Hodgkin’s lymphoma |
|Miscellaneous |Recurrent aphthous ulcers |
| |Delayed wound healing |
| |Xerostomia |
( Pharyngitis
➢ Very common condition; seen especially in children and caused mainly by viruses
➢ Approx. 15 to 20% of all pharyngeal infections are caused by beta-hemolytic streptococci—children between 5 and 15 years of age are most susceptible
➢ Important complications of beta-hemolytic strep pharyngitis are rheumatic fever and poststreptococcal glomerulonephritis
➢ Other forms of bacterial pharyngitis include diphtheria (pharynx and tonsils covered by adherent membrane) and gonorrhea (lesions often ulcerative)
➢ Noninfectious causes of pharyngitis include allergies, pollutants and smoking
( Tonsillitis
➢ Seen also predominantly in children and causative agents similar to pharyngitis
➢ The inflamed tonsils are usually covered by a yellow-white exudate
➢ The adenoids may also be affected and associated hyperplasia of these organs may cause blockage of the eustachian tube and otitis media
➢ Inadequately treated tonsillitis may result in tonsillar ulceration and peritonsillar abscess
2) Tumours
a) Benign epithelial proliferations
( Squamous papilloma
➢ Most common oral neoplasm—believed to be caused by HPV
➢ Painless exophytic mass with warty surface, usually < 1 cm and may be single
or multiple; preferred sites are the palate, tongue, gingivae and lips
b) Premalignant lesions
( Leukoplakia
➢ Clinical term for a white patch occurring on the surface of a mucous membrane
➢ In the mouth, the term is used to include only those white patches or plaques that will not rub off, and that are not caused by another oral disease
➢ Has been associated with tobacco smoking and alcohol abuse
➢ Most common in fifth to seventh decade; M>F
➢ Lesions may be localized or diffuse; vary from faintly translucent areas to thick fissured, indurated lesions
➢ 6% lesions will have carcinoma; additional 4% will undergo malignant transformation
( Erythroplakia (erythroplasia of Queyrat)
➢ Initially described as syphilitic lesion of the glans penis—then recognized to also occur on vulva and oral mucosa in patients who are not syphilitic
➢ Sixth to seventh decades; M=F
➢ Defined as bright red velvety plaques not due to any other condition (e.g.gingivitis, candidiasis, hemangioma); unlike leukoplakia, almost all lesions will prove to be squamous dysplasia or carcinoma on biopsy
c) Malignant epithelial proliferations
( Squamous cell carcinoma
➢ Account for majority of intraoral cancers; tobacco use and alcohol abuse implicated as causative factors; role of viruses (e.g. HPV,EBV) being investigated
➢ Predominantly affects males > 50 yr.
➢ Can present as mucosal ulcer, exophytic growth, endophytic growth, leukoplakia, erythroplakia or painless lymphadenopathy
➢ Commonest sites of involvement are the tongue, lip and floor of mouth
➢ Spread primarily by local extension and lymphatic dissemination; distant sites of involvement include lungs, bone and liver
➢ 5year survival rates are 75% for localized disease, 41% for regional cases and18% for cases with distant metastases
d) Nonepithelial tumours and tumour-like lesions
❖ Cysts of the gingiva, mucosa and jaw
❖ Benign soft tissue lesions (e.g. pyogenic granuloma, fibroma, schwannoma)
❖ Malignant soft tissue lesions (e.g. rhabdomyosarcoma)
❖ Lymphomas
❖ Odontogenic tumors (e.g. ameloblastoma)
❖ Tumours of the jaw (e.g. fibrous dysplasia, giant cell tumours, bone and cartilaginous tumours)
II. PATHOLOGY OF THE SALIVARY GLANDS
1) Obstructive Disorders
( Mucocele
➢ Most common of the obstructive disorders; results from trauma to minor salivary glands with extravasation and pooling of mucus in surrounding tissues
➢ Seen mainly in young persons; the lips are the favoured site
➢ Usually appear as small, fluctuant masses—large mucoceles of the floor of the
mouth are known as ranulas; these may extend into the neck
( Sialolithiasis
➢ This is the formation of stones (calculi) in the ducts of salivary glands
➢ The stones result from the calcification of an intraluminal nidus e.g. dried
secretions or cellular debris—they are composed mainly of calcium phosphate
➢ Inflammation of the salivary duct and stasis of saliva have been suggested as
predisposing factors—the submandibular duct is the most common site
➢ Peak incidence in the fourth and fifth decades
➢ The stones vary in size, surface texture and colour
➢ Recurrent infection of affected glands (secondary to obstruction) is common
2) Inflammation (Sialadenitis)
➢ Can be caused mechanical, physical, infectious and immunologic factors:
( Mechanical
➢ Mechanical obstruction of salivary ducts can be intraluminal (e.g. stones) or
extraluminal (e.g. tumours)
➢ It leads to chronic and recurrent sialadenitis that can result in partial or
complete destruction of the affected gland
( Physical
➢ Physical causes of sialadenitis include radiation e.g. administered during
treatment of head and neck cancers
➢ Initial acute inflammation is followed by chronic sialadenitis and fibrosis
◆ Infectious
❑ Acute suppurative sialadenitis
➢ Usually caused by Staphylococcus aureus and group A streptococci that enter salivary ducts from the oral cavity: reduced or absent salivation thought to predispose
➢ Ductal epithelium and acini are destroyed by invading inflammatory cells and microabscesses may form
❑ Viral sialadenitis
➢ Several viruses can cause sialadenitis including paramyxovirus (the mumps virus), coxsackieviruses A and B, influenza viruses and cytomegalovirus—of these mumps is the most common to involve the glands
❑ HIV-associated cysts of the parotid
➢ HIV infection can cause lymphadenopathy of intraparotid lymph nodes
➢ There is marked lymphoid hyperplasia which can be accompanied by the formation of keratin-filled cysts (salivary duct epithelium undergoes metaplastic change)
➢ Unilateral or bilateral enlargement of the parotids can result
❑ Tuberculosis
➢ Tuberculosis may involve intraparotid and paraparotid lymph nodes; infection of these nodes may originate from a tuberculous focus in the mouth or pharynx, or result from dissemination of pulmonary TB
➢ Can present as painless mass/masses mimicking a tumour
➢ Histologic examination will reveal the typical caseating granulomas and the findings can be confirmed with cultures and special stains
◆ Immunologic
❑ Sjogren’s syndrome
➢ Autoimmune disease characterized by the progressive lymphocytic infiltration and destruction of exocrine glands, particularly the salivary and lacrimal glands
➢ Clinical hallmarks are keratoconjunctivitis sicca, xerostomia, and rheumatoid arthritis; may also be assoc. with other autoimmune disesases e.g. SLE
➢ 90% patients are female; average age at diagnosis is 50 yr.
➢ Firm, diffuse, painless enlargement of the salivary glands, which is usually but not always bilateral, is the typical presentation
➢ Histologic hallmark is a lymphocytic sialadenitis—lymphoid follicles may be presentThese patients are at increased risk for non-Hodgkins lymphoma
3) Benign Tumours
( Pleomorphic Adenoma (Benign mixed tumour)
➢ Most common salivary gland tumour overall
➢ Accounts for 60 – 70% of parotid tumours, 40 – 60% of submandibular tumours, and 40 – 70% of minor salivary gland tumours
➢ Peak incidence between 30 and 50 years; female to male ratio 3:1
➢ Slowly-growing painless, firm masses—in the parotid, most occur in the superficial lobe
➢ A variety of growth patterns may be seen histologically—the basic components are epithelium, myoepithelium and stroma .
➢ Recurrence may occur if the tumour is inadequately excised.
( Warthin’s tumour (Papillary cystadenoma lymphomatosum)
➢ Slow-growing benign tumour that arises almost exclusively in the parotid
➢ 5 – 6% of parotid tumours; peak incidence 40 – 70 years; male to female ratio is 5:1.
➢ It is proposed that the tumour develops from parotid ductal epithelium present in lymph nodes within the gland.
➢ Most tumours measure 2-3 cm at diagnosis; tumours are bilateral in 7% of patients
➢ The histology is distinctive and pathognomonic—epithelial-lined cystic spaces showing papillary projections are present in a lymphoid stroma.
➢ As with pleomorphic adenomas, recurrence may occur if the tumour is incompletely removed.
4) Malignant Tumours
➢ Malignant salivary gland tumours are less common than benign ones; ratio of benign to malignant approximately 4:1
➢ The most common tumours are mucoepidermoid carcinoma, adenoid cystic carcinoma, acinic cell carcinoma and malignant mixed tumours.
( Mucoepidermoid carcinoma
➢ Most common malignant salivary gland tumour; accounts for 2-10% of major salivary gland tumours and 10-40% of minor salivary gland tumours
➢ Most common in 35-65 year age group; however, it can affect children and adolescents
➢ They are slowly growing firm masses that are often clinically indistinguishable from the more common pleomorphic adenoma, and range in size from 1-4 cm.
➢ Histologically these tumours are composed of epidermoid cells, mucus-secreting cells and intermediate cells; classified as low, intermediate and high-grade
➢ The histologic grade is directly related to prognosis—survival rate in patients with low-grade tumours is 90-100%; intermediate and high-grade tumours tend to show local invasion, recurrence, and metastases, with survival rates of 40-60%.
( Adenoid Cystic Carcinoma
➢ Account for 3-10% of salivary gland tumours— more common in minor salivary glands
➢ Twenty-five percent arise in major salivary glands, most commonly the submandibular
➢ May arise at any age, but occur most frequently in the 4th to 6th decades
➢ Patients with tumours in the major glands commonly present with a painful mass. Those in the minor glands can also produce respiratory obstruction
➢ Usually form well-defined masses, but histologically are seen to infiltrate surrounding tissues
➢ Perineural invasion is characteristic of this neoplasm, and this feature seems to account for the poor long-term outcome in patients with this tumour.
➢ Metastasis can occur to cervical lymph nodes or distant sites e.g. lung, bone, liver, brain
➢ 5-year survival rates as high as 70% have been reported, but rate declines to 5-15% at 20 years.
( Acinic Cell Carcinoma
➢ Relatively uncommon tumour; accounts for 2-3% of salivary gland tumours.
➢ Most often involves the parotid; most common malignant tumour involving >one salivary gland
➢ Most common in the 5th decade
➢ Range in size from 2-4 cm; most are solid, though cystic change can occur.
➢ These carcinomas are regarded as low-grade tumours—regional metastasis occurs in 5-10% of patients, but distant metastasis is rare. Five and 10-year survival rates have been reported as 82% and 68% respectively
NB. The following link can provide you with additional information and images for this topic:
SESHIRLEY/Oct 2005
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