Salivary gland tumours: A 16-year review at Jos …

Nigerian Journal of Clinical & Biomedical Research

Salivary gland tumours: A 16-year review

at Jos University Teaching Hospital, Jos

1

EC Otoh, 2BM Mandong, 1IS Danfillo, 1PH Jalo

1

Regional Center for Oral Health Research and Training

Initiatives (RCORTI), Jos, Nigeria

2

Department of Histopathology, Jos University Teaching

Hospital (JUTH), Jos, Nigeria

Correspondence:

Dr. Emmanuel Chukwuka Otoh

Basic Science & Research Division

Regional Centre for Oral Health Research & Training

Initiatives (RCORTI) for Africa

3, CBN Road, PMB 2067 Jos, Plateau State, Nigeria

Tel:+234 -73 - 462901 / +234-73- 612750/

+234 803 635 7247 / Fax:+234 -73 - 462901

E-mail: ecotoh@yahoo.co.uk

Key words: salivary gland, neoplasia, radiation,

pleomorphic adenoma, Nigeria

SUMMARY

There is a dearth of information on the history of

salivary gland tumours in northern Nigeria and the

objective of this study is to document the

epidemiology of salivary gland tumours as seen at the

Jos University Teaching Hospital (JUTH), Jos, Plateau

State, Nigeria. It is designed as a retrospective study

and made use of the duplicate histology reports and

case notes of all reported cases of salivary gland

tumours seen at the JUTH over a period of 16 years

which were retrieved from the histopathology

department of the hospital. Information on sociodemographic characteristics, histological type and

relevant clinical parameters were extracted and

entered for data analysis using the Brititsh Association

of Head & Neck Oncologists�� (BAHNO) Minimum

Dataset for Cancers. A total of 117 cases of

histologically confirmed salivary gland tumours were

seen during the period. The benign-malignant ratio

was 2.7:1 and the parotid gland was the most affected

site (52.1%). Pleomorphic adenoma (89.4%) and

mucoepidermoid carcinoma (22.6%)

respectively,

were the most common benign and malignant

tumours reported. Mucoepidermoid carcinoma occurs

commonly between the 2nd and 5th decades of life with

no gender predilection while pleomorphic adenoma

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Nigerian Journal of Clinical & Biomedical Research

occurs usually between the 2nd and 3rd or 4th decades of

life; with a fairly equal gender distribution (M : F= 1 :

1.2). Although there were greater delays in the

presentation of benign cases (30.4 �� 24.2 months) in

comparison with malignant cases (12�� 6.9 months), the

difference was not statistically significant (p=0.09).

INTRODUCTION

Geographical variations in the prevalent site and type

of salivary gland tumours have been reported in the

literature.1-6 The commonly involved sites include the

parotid and sub-mandibular glands and the minor

salivary glands of the palate, with the sublingual gland

being the least affected.2,3,5,6

The commonly reported tumours (benign and

malignant) include pleomorphic adenoma,

mucoepidermoid carcinoma, adenocystic carcinoma,

carcinoma ex-pleomorphic adenoma and adenocarcinoma.4,5,7,8,9,10 Studies in Nigeria and Africa showed

that salivary gland cancers constitute between 2.8%

and 10% of all head and neck malignancies.1,2,5,9

Certain risk factors, like radiation exposure, have been

associated with the development of malignant salivary

gland tumours.11 Most studies in Africa showed a

delay by patients in reporting to the hospital, with

most presenting with the late stage disease (stage

III/IV), whereas early reporting in developed

countries has greatly improved the survival of patients

diagnosed with these tumours.1,5,6,10,12,13

An earlier study of salivary gland tumours in

northern Nigeria decried the poor record of the

natural history of tumours in northern Nigeria due to

the long distances patients had to travel for treatment

and loss of patients to follow up.8 The commencement

of histopathology services at JUTH in 1986 was

expected to increase the number of referrals for biopsy

from the areas in north central Nigeria served by the

hospital. This study documents the epidemiology of

salivary gland neoplasia in the areas served by the

hospital.

METHOD

JUTH is one of the referral hospitals for histopathology

in the North Central Zone of Nigeria and receives

biopsy samples from both public and private hospitals

in the North Central Zone (Plateau, Nassarawa, Benue,

Kogi states and some states in the North Eastern Zone

52

Volume 1 ? Number 1 ? 2006

(Bauchi and Taraba states), with an approximate

population of about 14 million.

The ethical clearance for the study was obtained

from the Ethical Committee of JUTH. Only

histologically diagnosed salivary and extra-salivary

gland tumours were included in the study.

Socio-demographic information and history of

patient management (age, sex, occupation, ethnic

group, history of habits; history of symptoms, dates of

referral and 1st appointment, pre-treatment and

histological TNM staging of lesion, clinical and

histological diagnosis, dates of biopsy and dates of

biopsy report; definitive treatments and date of

discharge) were retrieved from pathology and medical

records of patients from January 1987 (the

commencement of histopathological services at JUTH)

until December 2002 were reviewed. The information

obtained were entered into data entry forms designed

and modified according to the pattern developed for

the British Association of Head and Neck Oncologists

(BAHNO) Minimum Dataset.14 The tumours recorded

were as classified by the 3rd Edition of the International

Classification of Diseases Oncology (ICD-O).15

The information was analyzed statistically using

the Microsoft Office 2000? Excel Package; SPSS 11+

and the STATCALCR statistical package of the Epi Info

Version 6.0 (1993). The student��s t test, Yates��

corrected, and Fisher��s exact tests were used to

determine areas of significant associations between

nominal variables such as prevalence rate and

duration of symptoms and to compare means in this

study with the reported findings from previous

studies. A p-value of 0.05 or less was considered

significant.

RESULTS

A total of 117 cases of histologically diagnosed salivary

and extra-salivary gland tumours were seen during

the period of study with a benign-malignant ratio of

2.7:1. Of these 117 tumours, 85 (72.6%) were benign,

while 32 (27.4%) were malignant. Plemorphic

adenoma (89.4%) was the most common benign

tumour and muco-epidermoid carcinoma (18.6%) the

most common malignant tumour seen. The prevalence

of other tumours is as shown in table 1.

Nigerian Journal of Clinical & Biomedical Research

The major salivary glands (67.5%), especially the

parotid gland (52.1%), were the most affected sites.

The intra-oral minor salivary glands were less affected

(5.1%), with the palate and unspecified intra-oral

glands constituting 1.7% each. No malignancy was

reported in any minor salivary gland site (table 1).

The age and sex distribution at presentation

among the patients presenting with salivary and extrasalivary gland tumours is shown in table 2. The mean

age at presentation was 34.2 �� 19.0 years with a range

of 5-90 years. Majority of the benign tumours (58.8%)

occurred during the 2nd-4th decades of life with a malefemale ratio of 1 : 1.2. Pleomorphic adenoma was more

commonly reported in the 2nd and 3rd decades of life,

with a peak in the 2nd decade (table 2). Its overall mean

age of occurrence was 29.95 �� 15.3 years (males = 31.9

�� 18.2 years; females = 28.4 �� 12.5 years).

Malignant tumours occurred most commonly in

the 4th-5th decades of life with an equal sex distribution.

Mucoepidermoid carcinoma was reported commonly

in the 2nd and 5th decades of life, with an overall mean

age of occurrence of 36 �� 14.4 years (males = 29.3 �� 15.3

years; females = 6 �� 5.7 years) (table 2).

The duration of symptoms is defined in this study

as the interval between the onset of symptoms and the

date of reporting at the hospital. Patients with benign

tumours of the major salivary glands delayed about

2.5 times longer than those with malignant lesions

(p=0.09). Specifically, patients diagnosed with

pleomorphic adenoma delayed for twice as long as the

patients diagnosed with its malignant variant (table 3).

DISCUSSION

The ratio of benign to malignant tumours is relatively

higher (p>0.05) than previously reported for Nigeria

and Tanzania1,2,5,10 (see table 4).

Table 1. Salivary gland tumours by ICD-O codes

Tumours

Major Salivary Glands

Minor Salivary Glands

Unspecified

glands

Total No.

(%)

Parotid

Submnd

Subling

Palate

Lip

Mouth

Extra-SG

Tonsils

Pleomorphic adenoma

31

12

1

2

1

1

4*

1

Monomorphic adenoma

3

-

-

-

-

--

-

-

-

3 (2.6)

Warthin��s tumour

-

-

-

-

-

1

-

-

1

2 (1.7)

23

76 (64.9)*

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Nigerian Journal of Clinical & Biomedical Research

Schwannoma

1

-

-

-

-

-

-

-

-

1 (0.85)

Cavernous lymphangioma

-

1

-

-

-

-

-

-

-

1 (0.85)

Cavernous hemangioma

1

-

-

-

-

-

-

-

-

1 (0.85)

Lymphangioma

1

-

-

-

-

-

-

-

-

1 (0.85)

Mucoepidermoid carcinoma

5

1

-

-

-

-

-

-

1

7 (5.9)

Adenoidcystic carcinoma

3

2

-

-

-

-

-

-

-

5 (4.3)

Squamous cell carcinoma

3

-

-

-

-

-

-

-

-

3 (2.5)

Acinic cell tumour

4

-

-

-

-

-

-

-

-

4 (3.4)

Ca. Ex Pleomorphic adenoma

3

1

-

-

-

-

-

-

-

4 (3.4)

Adenocarcinoma

1

-

-

-

-

-

-

-

-

1 (0.85)

Adenolympho carcinoma

1

-

-

-

-

-

-

-

-

1 (0.85)

Undiff. carcinoma

1

-

-

-

-

-

-

-

1

2 (1.7)

Unspecified carcinoma

3

-

-

-

-

-

-

-

-

3 (2.5)

Lymphoepithelioma

-

-

-

-

-

-

-

-

1

1 (0.85)

Non Hodgkin��s lymphoma

-

-

-

-

-

-

-

-

1

1 (0.85)

61

17

1

2

1

2

4

1

28

117

(52.1)

(14.4)

(0.85)

(1.7)

(0.85)

(1.7)

(3.4)

(0.85)

(23.7)

(100)

Other benign tumours

Total

TOTAL

(%)

* Includes 4 cases in other minor salivary gland sites like the Eye (2), Max. Antrum (1) and Neck (1)

Table 2a. Age and gender distribution of salivary gland tumours benign tumours

Age group

Pleomorphic adenoma

Sex

Male

Monomorphic adenoma

Female

Gender

not specified

Male

Female

Male

Female

Age

0-10

11-20

21-30

31-40

41-50

51-60

61-70

71-80

81-90

Unspecified adult

Unspecified age

2

6

6

5

2

3

1

1

4

4

13

10

7

3

1

4

1

3

1

-

1

1

-

1

1

-

2

1

1

1

4

19

18

13

5

4

1

2

1

9

9

Total

34

39

3

1

2

2

4

85

Table 2b. Age and gender distribution of salivary gland tumours �C malignant tumours

Age group

Sex

Mucoepidermoid carcinoma

Adenoidcystic carcinoma

Other malignant neoplasms

Total

M

F

U

M

F

U

M

F

Age

0-10

-

-

-

-

-

-

-

-

11-20

1

-

1

-

-

-

-

1

3

21-30

1

-

-

-

-

-

1

2

4

54

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Nigerian Journal of Clinical & Biomedical Research

31-40

-

-

-

-

-

-

4

2

6

41-50

-

3

-

1

1

-

1

-

6

51-60

-

-

-

-

1

-

-

2

3

61-70

-

-

-

-

-

-

1

1

2

71-80

-

-

-

-

-

-

1

-

1

81-90

-

-

-

-

-

-

1

1

2

Unspecified adult

1

-

-

-

-

-

1

-

2

Unspecified age

-

-

-

1

-

1

-

1

3

Total

3

3

1

2

2

1

10

10

32

Table 3. Duration of symptoms by site and tumour type

Site

Histological type

Duration of symptoms (months)

All salivary glands

benign

malignant

30.4 �� 24.2

12 �� 6.9

Parotid gland

benign

malignant

27.3 �� 28.2

12 �� 6.9

Submandibular gland

benign

malignant

30 �� 20.8

����

Minor salivary glands

benign

malignant

42 �� 25.5

����

Tumours

Duration of symptoms (months)

Pleomorphic adenoma

32.1 �� 24.5

Carcinoma. ex pleomorphic adenoma

16.3 �� 7.1

Relative to head and neck cancers, the 4.4%

prevalence of malignant salivary gland tumours in this

study is lower (p ................
................

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