Epidermal Cyst (Sebaceous Cyst)

The epidermal cyst — popularly often called a “sebaceous cyst” — is one of the most common benign growths of the skin. In fact it does not develop from fatty tissue but from the build-up beneath the skin of the cells that form the skin surface, and it is filled with a white substance called keratin.

It appears most often on the face, scalp, neck, back and trunk. It is usually a slow-growing, round, mobile swelling beneath the skin and most of the time causes no pain. Some cysts have a small black dot in the centre (the opening of the cyst).

Cysts can remain unchanged for a long time. However, they may occasionally become inflamed, causing redness, pain, swelling and discharge, in which case medical treatment may be needed. For cysts that recur or bother the patient, complete surgical removal is the most effective treatment.

Epidermal cysts are benign and usually pose no serious health problem. However, it is important that the correct diagnosis is made for any mass developing beneath the skin. With clinical examination and, where needed, ultrasonography or biopsy, it can be distinguished from other skin and soft-tissue tumours.