Polycystic disease of the parotid glands: case report of a rare entity and review of the literature.

We report a case of polycystic disease of the parotid glands. This is a rare disorder and we know of only two previous documented cases in the literature. The disease presents with painless enlargement of one or both parotid glands and is not associated with any clinical abnormality of salivation or with any apparent anomaly of the other salivary glands. Histologically, the overall glandular architecture is preserved but the lobules are all markedly distended by epithelial-lined cysts, which appear to be derived from the intercalated ducts. Characteristic congophilic laminated spheroliths are present within the cystic spaces. The condition must be differentiated from cystic neoplasms, particularly papillary cystic adenocarcinoma, and from various non-neoplastic disorders including sialectasia, retention cysts and lymphoepithelial cysts.