Histologic and fine-needle aspiration cytologic features of polycystic disease of the parotid glands: case report and review of the literature.

Polycystic disease of the parotid glands is a rare disorder, with only eight examples to our knowledge being reported in the literature. The disease presents as a painless enlargement of one or both parotid glands and does not appear to be associated with other disease processes within the head and neck, or with polycystic disease of the kidney, pancreas, or congenital fibrosis of the liver. The histology has been well described. The overall glandular architecture is preserved but the lobules are markedly distended by cysts whose lining appears to be intercalated duct in differentiation. Characteristic eosinophilic laminated spheroliths lie in many of the cystic spaces. Aspirate smears are characterized by a relatively clean background in which are distributed histiocytes, red blood cells, and small clusters of ductal epithelial cells. Polycystic disease of the parotid glands must be differentiated cytologically from mucous retention reaction, mucoceles, benign lymphoepithelial cysts, and cystic neoplasms, including Warthin's tumor, low-grade mucoepidermoid carcinoma, cystadenoma, and papillary cystadenocarcinoma.