Steatocystoma multiplex, also known as sebocystomatosis and epidermal polycystic disease, is characterized by multiple, epithelial-lined, sebum-filled dermal cysts that are distinguished by the presence of sebaceous glands within the cyst walls. These lesions may occur sporadically or in an autosomal dominant pattern of inheritance. Steatocystoma multiplex may also occur with syndromes such as pachyonychia congenita and Alagille syndrome. The development of steatocystomas is thought to be associated with the mutation in keratin 17 on chromosome 17q21.2. To date, 18 distinct mutations of KRT17 associated with steatocystoma multiplex have been identified. Solitary lesions that occur sporadically are termed steatocystoma simplex.

Steatocystoma multiplex tends to present during adolescence or young adulthood. Lesions typically occur on the trunk, upper arms, scrotum, axillae, or chest, but in severe cases, lesions may be generalized. Lesions are asymptomatic, skin-colored or yellowish dermal papules or nodules. When the lesion is incised, oily material may be expressed. Individual cystic lesions may become infected, leading to sinus formation and scarring. When multiple lesions become inflamed, it has been proposed that this variant be termed steatocystoma multiplex suppurativa.

Long-term management is difficult, and spontaneous resolution is not expected to occur.