<Li> Epidermoid cysts (also termed epidermal cysts, infundibular cyst), or </Li> <Li> Pilar cysts (also termed trichelemmal cysts, isthmus - catagen cysts). </Li> <P> Both of the above types of cyst contain keratin, not sebum, and neither originates from sebaceous glands . Epidermoid cysts originate in the epidermis and pilar cysts originate from hair follicles . Therefore, technically speaking they are not sebaceous cysts . "True" sebaceous cysts, cysts which originate from sebaceous glands and which contain sebum, are relatively rare and are known as steatocystoma simplex or, if multiple, as steatocystoma multiplex . </P> <P> Medical professionals have suggested that the term sebaceous cyst be avoided since it can be misleading . In practice, however, the term is still often used for epidermoid and pilar cysts . </P>

What is the stuff in a sebaceous cyst