A cyst usually is a slow-growing lump that can move easily under the skin. The term “sebaceous cyst” refers to either an epidermoid cyst, which originates from the skin, or a pilar cyst, which comes from hair follicles.
These cysts are closed sacs that can be found under the skin of the entire body (except the palms of the hands and soles of the feet). A foul odor may be noticed from the overlying skin.
Sebaceous cysts may be caused by blocked glands or swollen hair follicles in the skin. Trauma to skin has been reported, as well. Cysts sometimes are inherited.
The main symptom of a sebaceous cyst is a small lump under the skin. The lump is usually not painful. In some cases, however, cysts can get inflamed and become tender to the touch. The skin on the area of the cyst may be red and/or warm. Drainage from the cyst will appear grayish-white and cheese-like, and will have a foul smell.
Usually, a doctor can diagnose sebaceous cysts with a simple examination of the skin. In some cases, the doctor will perform a biopsy to rule out other skin growths.
In most cases, sebaceous cysts can be ignored, as they usually are not dangerous. If a small cyst becomes inflamed, a doctor can inject it with a steroid drug to reduce swelling. A doctor may drain a cyst that is large, tender, or inflamed. Larger cysts may need to be removed if they cause hair loss on the scalp or interfere with clothing.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 12/05/2016