Steatocystoma multiplex

Steatocystoma multiplex is a benign, usually autosomal dominant congenital condition in which a person develops multiple small cysts, generally 2 to 20 millimeters across but sometimes swelling to 4 to 6 centimeters when inflamed. The cysts form from abnormal lining of the sebaceous ducts that carry oil from skin glands and have been linked to defects in Keratin 17; most cases run in families, though sporadic cases can appear as new mutations with no prior family history. Cysts typically first appear around puberty, likely triggered by hormonal stimulation of hair follicles and oil glands, and present as soft to firm, semi-translucent bumps filled with an oily yellow liquid. They occur most often on the chest but can also appear on the abdomen, upper arms, armpits and face, and when inflamed can become intensely painful and interfere with everyday movement.