tumor of salivary gland

1. List the tumours of salivary glands. (C1)

Benign

• Pleomorphic adenoma

• Warthin tumour

Malignant

• Mucoepidermoid carcinoma

• Adenoid cystic carcinoma

2. Describe the clinicopathological features of (C2)

a) Pleomorphic adenoma.

• Most common salivary gland neoplasm

• represent about 60% of tumours in the parotid

• Benign tumours that consist of a mixture of ductal (epithelial), myoepithelial, and mesenchymal cells (mixed tumors)

• Little is known about the origin of pleomorphic adenomas, but radiation exposure increases risk

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Gross:

• rounded, well-demarcated masses, encapsulated

cut surface is gray-white with myxoid and blue translucent areas of chondroid (cartilage-like) stroma

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Histology:

-Heterogeneity.

-The epithelial elements resembling ductal cells or myoepithelial cells are arranged as ducts, acini, irregular tubules, strands, or sheets of cells.

-These elements are typically dispersed within a background of loose myxoid and hyaline tissue containing islands of cartilage and, rarely, foci of bone

-Islands of well-differentiated squamous epithelium may also be present.

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• present as painless, slow-growing, mobile, discrete masses within the

parotid or submandibular areas or in the buccal cavity.

• The rate of recurrence following parotidectomy is about 4%.

• Recurrences occur months to years after surgery.

• Rates of malignant transformation in pleomorphic adenoma correlate with

age of the lesion

2. Describe the clinicopathological features of (C2)

b) Warthin tumour.

-second most common salivary gland neoplasm.

-It is unique in that it arises almost exclusively in the parotid gland.

- Warthin tumours are benign

-occur more commonly in males than in females, usually in the fifth to seventh decades of life.

-The risk is increased eightfold in smokers.

-Most Warthin tumours are unifocal, but about 10% are multifocal and 10% bilateral.

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Gross:

-round to oval encapsulated masses, 2 to 5 cm in diameter, and readily palpable within the superficial parotid gland.

-Cut surface reveals a pale gray surface punctuated by narrow cystic or cleft-like spaces filled with mucinous or serous secretions and frequently narrowed by polypoid projections of

lymphoepithelial elements.

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Histology:

-The lining is composed of a double layer of oncocytic cells; the innermost layer is columnar, while cuboidal cells occupy the outer layer

-Secretory cells dispersed in the inner layer account for secretions within the dilated lumen. Foci of squamous metaplasia may be present.

2. Describe the clinicopathological features of (C2)

c) Mucoepidermoid carcinoma.

-The most common primary malignant tumour of salivary glands representing about 15% of all salivary gland tumours

-Most (60% to 70%) occur in the parotids

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Gross:

• Mucoepidermoid carcinomas can grow as 8cm in diameter

• Although they appear circumscribea, well defined capsule is not present

• The tumors are often infiltrative at the margins.

• In transection, mucoepidermoid carcinomas are pale, gray-white and frequently contain small, mucin- containing cysts.

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Histology: demonstrates cords, sheets, or cystic configurations of squamous,mucous, or intermediate cells that have squamous features and small to large mucus-filled vacuoles

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Clinical course

-The clinical course and prognosis of mucoepidermoid carcinomas reflects the histologic grade.

-Low-grade tumors may invade locally and recur in about 15% of cases, but they rarely metastasize.

The 5-year survival rate is more than 90%.

-High-grade neoplasms and intermediate-grade tumors are invasive and difficult to excise.

Up to 30% recur and 30% metastasize to distant sites, yielding a 5-year survival of only 50%.

2. Describe the clinicopathological features of (C2)

d) Adenoid cystic carcinoma.

• Parotid and submandibular glands are most commonly affected.

• 50% of these relatively uncommon tumours occur in the minor salivary glands (particularly the palatine glands).

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-Gross-

small, poorly encapsulated, infiltrative, gray-pink lesions

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Histology:

-composed of small cells with dark, compact nuclei and scant cytoplasm.

-The tumour cells are organized in a cribriform growth pattern that resembles swiss cheese.

-The spaces between the tumour cells are often filled with hyaline material thought to represent excess basement membrane

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Clinical course

• Adenoid cystic carcinomas are unpredictable, slow growing tumours that tend to invade perineural spaces

• They regularly recur

• 50% or more eventually disseminate to distant sites including bone, liver, and brain, sometimes decades after attempted removal.

• Adenoid cystic carcinomas arising in the minor salivary glands tend to have a poorer prognosis than those arising in the parotid glands.