A ciliated cyst as a component of pleomorphic adenoma of the parotid gland

A large cyst, lined with ciliated cells (ciliated cyst), was found as a component of a pleomorphic adenoma of the left parotid gland in a 34‐year‐old Japanese man. The dimensions of the tumor were 25 × 33 mm and it consisted of a solid mass with a centrally located cyst 20 × 23 mm. which contained yellowish‐brown material of muddy consistency. The tumor was encapsulated and the solid mass had features typical of a pleomorphic adenoma. The inner surface of the cyst was lined with ciliated cells and scattered mucus‐secreting cells in addition to cuboidal‐to‐flattened cells. In some regions, the neoplastic cells of the pleomorphic adenoma were exposed to the cavity of the cyst. A histological transformation from ciliated cells to pleomorphic adenomatous cells was also observed. These findings indicated that the ciliated epithelium was an element of the tumor. This is the first report, to our knowledge, of a ciliated cyst derived from some elements of a pleomorphic adenoma of the salivary gland.