What is a sebaceous cyst?

A sebaceous cyst is a closed sac found under the skin, usually on the trunk, neck, or face. It usually is a slow-growing lump that can move easily under the skin. Sebaceous cysts are filled with a oily or cheese-like matter and usually are painless. In some cases, however, cysts can get inflamed and become tender to the touch. Sebaceous cysts also are called epidermal cysts, keratin cysts, or epidermoid cysts.

What are the symptoms of sebaceous cysts?

The primary symptom of a sebaceous cyst is a small lump under the skin. The lump usually is not painful, but there may be redness, increased temperature of the skin on the area of the cyst, or tenderness to the touch. Drainage from the cyst will appear grayish-white and cheese-like and will have a foul smell.

What causes sebaceous cysts?

Most often, sebaceous cysts come out of hair follicles. Cysts also can form as a result of trauma to the skin.

How are sebaceous cysts diagnosed?

Usually, a doctor can diagnose a sebaceous cyst with a simple examination of the skin. In some cases, the doctor will perform a biopsy to rule out certain conditions.

How are sebaceous cysts treated?

If a small cyst becomes inflamed, a doctor can inject it with a steroid drug to reduce swelling. A doctor may surgically remove a cyst that is large, tender or inflamed.