History: Proliferation of epidermal cells within a circumscribed space of the dermis gives rise to epidermal or epidermoid cysts. Epidermoid cysts of the genitals are common in the general population and may appear as a mass in the breast, the vulva, the clitoris, the penis, the scrotum, or the perineum. This young man developed multiple epidermoid cysts on the scrotum over several years.