Spindle cell myoepithelioma of the parotid gland

ABSTRACT

Myoepithelioma was recognized as a histological distinct entity by the World Health Organization (WHO) in 1991. Myoepithelial cells are believed to be of ectodermal origin. In salivary glands, the myoepithelial cells that surround the intercalated ducts are spindled, which is in contrast to the large stellate ones that envelop the acini. Myoepithelioma is a benign salivary gland tumor that consists entirely of myoepithelial cells. A 53-year-old man presented with a 1-year history of a painless mass originating from the right parotid gland. The mass grew rapidly reaching a size of approximately 6 cm. The patient had no facial paralysis. The authors performed right parotidectomy. Immunohistochemistry study of this tumor showed that it was positive for vimentin, positive for S-100, focally positive for pancytokeratin, and focally positive for p63 and that it had a Ki-67 labeling index (below 10%). Additionally, the tumor was negative for epithelial membrane antigen, negative for actin, negative for desmin, negative for CD34 and negative for anaplastic lymphoma kinase. The authors present a case of benign spindle cell myoepithelioma of the parotid gland in a 53-year-old man diagnosed after immunohistochemistry study, describing its importance, along with a brief review of the literature.