Epidermal cysts are slow-growing benign cysts containing material that is keratinous (keratinous or epidermal inclusion cyst, sebaceous cyst, milia), follicular (pilar cyst, or wen), or sebaceous (steatocystoma). They frequently occur on the scalp, ears, face, back, or scrotum.
On palpation, the cystic mass is firm, globular, movable, and nontender; cysts range from about 1 to 5 cm in diameter. This kind of cyst seldom causes discomfort unless it has ruptured internally, causing a rapidly enlarging, painful foreign body reaction and abscess. Keratinous cysts, the most common, often are surmounted with a punctum or pore; their contents are cheesy and often fetid (due to secondary bacterial colonization). Milia are minute superficial keratinous cysts noted on the face.
Cysts may be left or removed. A small incision may be made to evacuate the contents, then the cyst wall itself should be removed with a curet or hemostat; otherwise, the lesion will recur. Surgical excision with complete removal of the cyst wall is also effective. Internally ruptured cysts should be incised and drained; a gauze drain is inserted and removed after 2 to 3 days. Antibiotics are not needed unless cellulitis is present. Milia may be evacuated with a #11 blade.
Last full review/revision September 2008 by Daniel W. Collison, MD
Content last modified February 2012