This document discusses malignant tumors of the salivary glands. It covers risk factors like smoking, alcohol consumption and radiation exposure. It also discusses various types of salivary cancers like acinic cell carcinoma, mucoepidermoid carcinoma and adenoid cystic carcinoma. For each cancer, it describes characteristics like prevalence, presentation, histology, treatment options and prognosis. It highlights the importance of surgery and radiation therapy in treating these cancers. Molecular techniques are providing new insights but clinical applications are still limited.

1. Malignant tumours of the salivary
glands
In great Britain, the incidence of malignant salivary neoplasm is 1.2% per 100000.
1. Salivary malignancy increases with increased smoking & alcohol consumption.
2. Ionizing radiation is also well-documented cause.
3. Livestock feed processing has an increased risk of malignant salivary neoplasm( aflatoxin B1).
4. Diet ; polyunsaturated fatty acids seems to exert beneficial effect. Decrease intake of
polyunsaturated fatty acid inverse relationship with salivary malignancy.
5. EBV infection.
Molecular biology of salivary cancer
Immunohistochemical markers of prognostic interest in salivary malignancy include the following
1. Proliferating cell nuclear antigen(PCNA) immunoreativity is significantly increased in
malignant salivary disease compared with benign disease.
2. Ki-67(protein product of gene) is a useful marker in adenoid cystic carcinoma.
3. Bcl-2 expression is relatively low in salivary carcinoma.
4. Fibroblast growth factor 1 & 2 & fibroblast growth factor receptor 1 are overexpressed
in human salivary malignancy.
5. Oestrogen &/ or progestrone receptors are expressed in some malignant salivary
tumours suggesting an opportunity for endocrine intervention.
Molecular techniques are yielding a host of interesting data but as yet none of clinical relevance
other than disproving viral theories of salivary oncogenesis especially EBV, HPV, Herpes virus & CMV.
The classification &histology of malignant salivary tumours
1. Acinic cell carcinoma;
2. Mucoepidemoid carcinoma;
3. Adenoid cystic carcinoma;
4. Polymorphous low-grade adenocarcinoma;
5. Papillary cystadenocarcinoma;
6. Adenocarcinoma;

2. 7. Carcinoma ex pleomorphic adenoma;
8. Malignant mixed tumour;
9. Squamous cell carcinoma;
10. Undiffierentiated carcinoma.
Acinic cell carcinoma(usually bilateral)
Acinic cell carcinoma is often regarded as a low grade malignancy. Bilateral salivary malignancy is
very rare but acinic cell carcinoma is the most common after Warthin’s tumour(benign)
Clinically acinic cell carcinoma presents as a painless lump, usually in the parotid gland. It is
commonly a solitary encapsulated lesion with well-defined margin.
Histological diagnosis is difficult& the differential diagnosis may include thyroid, mucoepidermoid &
myoepithelial carcinoma, oncocytoma & metastatic renal cell carcinoma.
Although acinic cell carcinoma almost certainly has the best survival of any salivary cancers it has a
long natural history with a 15- year survival rate of only 55%.
Treatment should probably involve both total or near total parotidectomy with preservation of the
facial nerve unless involved. Neck dissection & post-operative radiotherapy outcomes are limited.
Mucoepidermoid carcinoma
This tumour is the most common of the salivary malignancies, accounting for one-third of cases.
Often presenting as a painless mass at the more benign end of the spectrum of this tumour to more
aggressive cancers presenting with pain , swelling & facial palsy.
In high-grade cancers, lymph node metastases occur in nearly three-quarters of patients at
presentation.
In case of mucoepidermod carcinoma, there are mucous secreting cells, epidermoid cells &
intermediate cells.
Mucoepidermoid carcinoma may be useful histological classification in term of high grade & low
grade.
Low grade tumours tend to be cystic whereas high grade tumour tend to be solid with area of
necrosis & haemorrhage.
1. For most favourable tumours a superficial parotidectomy with preservation of facial nerve.
2. Radical excision is necessary for patients with large / high grade tumours. An associated
elective neck dissection to include level 1, 2 & 3 for the N0 neck would be appropriate.
Postoperative irradiation to the primary site & neck must be carried out in high grade
tumour.

3. Adenoid cystic carcinoma
Almost one-third of adenoid cystic carcinoma develop in major salivary glands.
Forty percent are locally advanced at the time of presentation.
11% have distant metastases at presentation.
There are three histological subtypes; solid 25%, cribriform40%, & tubular 20%.
Solid pattern is associated with poorer survival than other types.
This disease has a very long history cure never achieved with 100 % recurrence at 30years.
Adenoid cystic carcinoma have predisposition to invade & spread along peripheral nerves.
Carcinoma ex pleomorphic adenoma
These tumours account for upto 10% of all malignant salivary cancer. It is very rarely develop within
a pre-existing pleomorphic adenoma( 3%) although the risk of malignancy may increase to as much
as 10% by 15 years. Malignant transformation most commonly took place
1. in men over 40 years of age,
2. in tumours of deep lobe,
3. in solitary nodule greater than 2 cm &
4. in those with history of a previous operation.
Histological classification type
1. true carcinoma in a pleomorphic adenoma; most common type
2. carcinosarcoma in which both components of the tumour are malignant & can metastasize.
3. Metastasizing mixed tumour( metastases contain malignant element & structure typical of a
benign tumour).
4. Noninvasive carcinoma or carcinoma in situ in a pre-existing benign pleomorphic adenoma.
The prognosis of carcinoma ex pleomorphic adenoma is poor. With cause-specfic survival at 5 years
of 40%, 10 years 24%, 15years 19%.
During follow up,one- quarter of patients develop lymph node disease & one-third develop distant
metastases.
Undifferentiated carcinoma
Histologically identical to nasopharyngeal carcinoma, later needs to be excluded as primary site.
It is very unusual to achieve cure of the neoplasm with median survival figures of 30 months.
Treatment with radiation.

4. Lymphoma
Three criteria for the diagnosis of this disease
1. Extraglandular lymphoma must not be present.
2. There is histological proof that the lymphoma involves the gland parenchyma & not the
intraglandular lymph nodes;
3. Immunohistochemical screening must confirm the presence of lymphoma markers.
Most lymphoma involve the salivary gland as part of a regional disease.
In general , low grade non-Hodgkin lymphoma is either not treated at all or if it is conservative
monoclonal management is undertaken with drugs such as chlorambucil.
High-grade lesion are usually treated aggressively with complex regimen such as VAPEC-B.
Both have median survival of approximately eight year.
Best clinical practice(adenoid cystic carcinoma)
Diagnostic work up should be include MRI of the primary site& neck with CT of the lungs, liver &
possibly the primary site if bone involvement is a likelyhood, as well as isotope bone scans for
mestastases.
Treatment is with radical surgery to the primary site without elective neck dissection & with post-operative
radiotherapy to achieve the maximum duration of locoregional control.
Large tumour are almost inevitably associated with nerve involvement. If gross nerve involvement or
frozen section of nerve involvement is found at operation, the nerve should be sacrifice &
immediate nerve grafting carried out.
The role of chemotherapy appears limited , with some response possibly with Cisplatinum.