Epidermal cyst or sebaceous cyst of the ovary

Epidermoid cysts are benign cysts, lined by mature keratinizing squamous epithelium but without hair (unlike dermoids). These lesions represent less than 0.25% of all ovarian neoplasms. Two main theories exist regarding the etiology: This may be a monophyletic variant of a dermoid or teratoma with only the epithelial component present, resulting in a highly differentiated lesion. Alternatively, epidermoid cysts may arise from epithelial cell nests in the ovary similar to those seen in Brenner tumors. The cysts can contain keratin and other sebaceous material. There is a similar counterpart tumor that occurs in the testes.