DISEASES OF THE DIGESTIVE SYSTEM Eman MS Muhammad

DISEASES OF THE SALIVARY GLANDS

INFLAMMATION OF THE SALIVARY GLANDS (1) Acute suppurative parotitis: Predisposing factors: (a) Lack of oral hygiene (b) Diminished flow of saliva as in fevers. Cause: Staphylococcal and streptococcal infection usually by the way of the parotid duct.

Pathology: The gland is hyperemic, swollen, and may show pus formation. Complications: (a) Retropharyngeal abscess (b) Pyemia (2) Mumps (epidemic parotitis): Definition: Systemic viral droplet infection in children mainly affecting the parotid glands.

Pathology: Non-suppurative inflammation of both parotid glands. The aciner epithelium shows degeneration and cytoplasmic inclusions. The interstitial tissue is congested and infiltrated by lymphocytes and macrophages. Fibrosis may follow.

Complications: are rare: (a) Orchitis specially in adults. Fibrosis may cause sterility (b) Oophoritis, pancreatitis, mastitis and meningoencephalitis. Causes of parotid enlargement: (a) Suppurative parotitis (b) Mumps (c) Mickulicz disease (d) Parotid calculi (e) Parotid tumors

TUMOURS OF THE SALIVARY GLANDS I. Benign tumors: (1) Pleomorphic adenoma (benign mixed salivary gland tumor): The commonest benign tumor of the salivary glands. Usually affects the parotid gland (90%). More common in females.

Gross picture: A slowly growing capsulated tumor arising from the lower part of the parotid gland. The tumor forms a round or oval lobulated mass 2-5 cm in diameter. The consistency is firm and rubbery. The cut surface is grayish white with soft myxomatous areas, blue translucence chondroid areas and cystic areas.

A heterogenous structure of: Microscopic picture: A heterogenous structure of: (a) Epithelial elements form ducts, acini, tubules and sheets of cells. They are of ductal and myoepithelial origin. The cells lining ductal and glands are cuboidal or columnar. Small, dark spindle myoepithelial cells underlie the cubical epithelium. The myoepithelial cells may form strands or islands

(b) Loose connective tissue, myxoid tissue, chondroid matrix and rarely bone. The epithelial and mesenchymal elements are intermixed and one of them may predominate.

Behavior: The tumor has a slow rate of growth. Recurrence after surgical removal may occur because there are tiny prolongations of tumor tissue extending beyond the capsule. The recurrent tumor usually appears as multiple separate nodules. The tumor may undergo malignant change.

(2) Monomorphic adenomas: Rare tumors and include adenolymphoma, oxyphil, clear cell, tubular, basal-cell, trabecular and sebaceous adenomas. (3) Adenolymphoma (Papillary cystadenoma lymphomatosum): Occur in the parotid gland. Gross picture: Round or oval capsulated tumor. The cut surface shows cystic spaces with papillary projections. The spaces contain mucinous gray or pale brown secretion.

Microscopic picture: The cystic spaces are lined by acidophilic tall columnar cells which also cover the papillary projections. Typically, there is an underlying layer of smaller cuboidal or polygonal cells. Mucus-secreting cells are dispersed between the tall columnar cells and account for the secretion. The stroma contains lymphoid tissue with germinal centers.

II. Malignant tumors: Malignant mixed salivary gland tumor: Arises as a malignant change in a benign mixed tumor. Rapid increase in size, induration, fixation, pain and facial paralysis occurs. Cut section the tumor is friable and shows areas of necrosis and hemorrhage. Microscopically the tumor is adenocarcinoma, adenoid cystic carcinoma, mucoepidermoid carcinoma or undifferentiated carcinoma. The tumor spreads by lymphatics to the upper cervical lymph nodes and later on by blood to the lungs, bones, liver and brain.

(2) Mucoepidermoid carcinoma: Commonly affects the parotid. The tumor consists of three types of cells, squamous cells, mucus secreting cells and intermediate cells. The cells form cords, sheets, or cystic spaces. According to cellular anaplasia the tumor is either well, moderately or poorly differentiated. Metastasis affects the regional nodes, lung, bone and brain.

(3) Adenoid Cystic Carcinoma (Cylindroma): Uncommon tumor in major salivary glands, but forms 20% of minor salivary gland tumors. Grossly similar to pleomorphic adenoma. Microscopically composed of small cells with dark nuclei and scanty cytoplasm. The cells form cystic or alveolar spaces producing the so called cribriform pattern. The spaces contain eosinophilic granular material or mucin. The tumor is slowly growing. Distant spread may occur, commonly by blood, rarely by lymphatics.

(4) Acinic cell tumor: Small tumor, often encapsulated. The cells simulate the serous cells of the salivary glands. The cells are large, rounded or polygonal and arranged as sheets or acini. The cytoplasm is clear or finely granular and basophilic. Tumor cells show little anaplasia and few mitosis. The tumor grows slowly, may recur and rarely metastasize.

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