A Case of Epidermal Cyst with Ossification

Abstract

A 49-year-old Japanese woman visited our clinic for the evaluation of a slowly progressing, well-circumscribed subcutaneous tumor on her back with a 3-year history. The tumor was excised under local anesthesia. A histopathological examination revealed that the cyst consisted of keratinous material covered by a squamous epithelium with a granular layer in the dermis. Moreover, focal ossification was observed beside the cyst wall. Epidermal cysts are common skin tumors composed of a cyst wall formed from epidermal cells and keratinous material. However, it is rare for epidermal cysts to be accompanied by ossification.