A sebaceous cyst is a term commonly used to refer to either: Epidermoid cysts (also termed epidermal cysts, infundibular cyst) Pilar cysts (also termed trichelemmal cysts, isthmus-catagen cysts) Both of the above types of cysts contain keratin, not sebum, and neither originates from sebaceous glands. Epidermoid cysts originate in the epidermis and pilar cysts originate from hair follicles...