Sebaceous Cysts


What Is It?

A sebaceous, or epidermal cyst, is a small, movable lump under the skin that appears when surface skin cells move deeper within the skin and multiply. These cells form the wall of the cyst and secrete a soft, yellowish substance called keratin, which fills the cyst. If the wall is ruptured, the keratin is discharged into the surrounding skin, which causes irritation and inflammation.

The cysts may remain small for years or they may continue to increase in size. They are rare in children but common in adults. Both sexes are affected equally.

Sebaceous cysts are not cancerous.


A cyst produces a movable, dome-shaped, smooth-surfaced mass that varies in size from a few millimeters to several centimeters. Sebaceous cysts appear primarily on the face, ears, chest and back, but can occur on almost any skin surface.


Your doctor can examine the swelling and tell you if you have a cyst.

Expected Duration

A cyst may disappear on its own or remain indefinitely. Some cysts progressively increase in size.


There is no way to prevent sebaceous cysts.


A sebaceous cyst usually does not need to be treated unless it is infected or is causing a cosmetic problem. Infected cysts usually are treated by draining the fluid and the cells that make up the cyst wall. You also may be treated with antibiotics. If a cyst is causing irritation or cosmetic difficulty, your physician can remove it by making a small incision in the skin, and emptying the contents of the cyst and its wall.

When To Call A Professional

If you have a swelling on your skin that lasts for more than two weeks, contact your doctor, especially if it is painful.


The prognosis for sebaceous cysts is excellent. Many cysts have no symptoms and will go away on their own. Cysts can recur. Drainage or surgical removal of cysts usually has no complications or side effects.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.