Orbital invasion by squamous cell carcinoma arising in multiple epidermoid cysts.

Epidermal or epidermoid cysts usually are benign, solitary-growing masses located in the mid- or lower dermis. They are believed to derive from pilosebaceous units and are lined with an epidermis-like epithelium including a granular cell layer. The occurrence of multiple epidermal cysts on the scalp of nonsyndromic patients is extremely rare. Although the presence of squamous cell carcinoma in the wall of an isolated epidermoid cysts is well documented in the dermatological literature,, the authors are not aware of any article in the English literature describing orbital invasion by a carcinoma developed in isolated or multiple epidermoid cysts.