Epidermoid Cysts, also known as sebaceous cysts, are the most common cyst of the skin. It ranges in size from a few millimeters to a few centimeters. Its contents are a cheesy, malodorous mixture of lipid and keratin. Cysts can stay quiescent, or they can become painful and inflamed and rupture. Treatment varies depending on discomfort, location and size, and includes injections of cortisone, incision and drainage, or an excision.