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Cutaneous Cysts

(Epidermal Inclusion Cyst; Milia; Pilar Cyst)

by Denise M Aaron, MD

Cutaneous cysts are common slow-growing lumps. Epidermal inclusion cysts contain a cheesy, foul-smelling substance composed of skin secretions.

Epidermal inclusion cysts, often incorrectly referred to as sebaceous cysts, are flesh-colored and range from ½ to 2 inches (about 1 to 5 centimeters) across. They often have an enlarged pore overlying them. They can appear anywhere but are most common on the back, head, and neck. They tend to be firm and easy to move within the skin. Epidermal cysts are not painful unless they burst under the skin and become inflamed or infected.

Milia are tiny, superficial epidermal inclusion cysts. They occur most often on the body and least often on the face or scalp.

Pilar (trichilemmal) cysts may appear identical to epidermal inclusion cysts but have a different origin in the skin. About 90% of pilar cysts occur on the scalp. The tendency to develop pilar cysts may be inherited.

Cutaneous cysts can be removed surgically after an anesthetic is injected to numb the area. The cyst wall must be removed completely or the cyst will grow back. Cysts that have burst under the skin need to be cut open to drain. Tiny cysts that are bothersome can be lanced and drained.