Papillary cystadenoma of the lower lip exhibiting ciliated pseudostratified columnar epithelium: report of a bizarre case and review of the literature.

BACKGROUND: Salivary gland tumors are uncommon and constitute 2-6.5 % of all head and neck neoplasms. Tumors of minor salivary gland origin account for less than 25 % of all salivary gland neoplasms. Papillary cystadenoma of salivary glands is a rare benign epithelial neoplasm characterized by multicystic growth in which the epithelium exhibits adenomatous proliferation. Papillary cystadenoma of minor salivary glands most frequently involves the lip, buccal mucosa, and palate. This tumor typically presents as a slow-growing, painless mass, usually with diameter of less than 1 cm and clinical resemblance to a mucocele. Although most papillary cystadenomas are predominantly of one cell type, a regional variability may be present. CASE REPORT: We present a case of papillary cystadenoma of the minor salivary glands in a 58-year-old patient exhibiting an upper respiratory tract epithelium, a profoundly atypical benign tumor. DISCUSSION: This type of minor salivary gland tumor epithelium in the lower lip may be the result of a metaplastic process or simply another neoplastic manifestation of papillary cystadenoma. As far as the differential diagnosis of this entity is concerned, it is important to distinguish it from papillary cystadenoma lymphomatosum (Warthin's tumor), low-grade mucoepidermoid carcinoma, the papillary-cystic variant of acinic cell carcinoma, and cystadenocarcinoma Recognition of this lesion is important for the clinician since the differential diagnosis includes lesions with similar clinical appearance and infiltrative behavior.