A case of pleomorphic adenoma of the upper lip

An electron microscopic study

Abstract

Pleomorphic adenoma is the common oral region neoplasm. The glands most frequently affected by this tumor are the parotid of the major salivary glands and the palate of the minor salivary glands. However, it is said that this tumor rarely develops on the lip.
We have recently experienced one case of pleomorphic adenoma on the upper lip.
This patient, a 58-year-old man, was referred to our hospital with a chief complaint of a mass on the upper lip. The tumor was completely resected under local anesthesia. The removed mass measured 0.5×0.6×0.6 cm, was well encapsulated, and the cut surface was yellowish white and solid.
Light microscopic findings showed that the parenchima of the tumor consisted of cuboidal or polygonal cells and that cells which conform ducts consisted of flattened monolayer cells. Electron microscopic findings showed that cells which conform ducts consisted of cells with the features of both intercalated duct cells and myoepithelial cells and that the parenchima of the tumor consists of cells similar to myoepithelial cells.
Histological diagnosis was pleomorphic adenoma, suggesting that this tumor originated from epithelial tissues.