Skin Spots: What Is an Epidermoid Cyst?

Health Writer
Medically Reviewed

Have you ever developed what looks like a whitehead, but it just won’t go away, even after you squeeze it? You probably have an epidermoid cyst.

Epidermoid cysts range in size from a few millimeters to up to several centimeters (more than an inch), and can occur anywhere on the body, though more often on the face, base of ears, and trunk. They can arise from the site of a whitehead or blackhead or after trauma to the skin.

They don’t feel attached to underlying tissue when you try to move them. And although epidermoid cysts can become red, painful, or swollen, they are unlikely to be infected with bacteria and are not contagious.

“Epidermoid cysts are collections of dead skin that form in a sac,” explains Daniela Kroshinsky, M.D., director of inpatient dermatology at Massachusetts General Hospital in Boston and a spokeswoman for the American Academy of Dermatology. “There is a little dot opening to the cyst and then there is white around it.”

Because they aren’t harmful, epidermoid cysts typically don’t need to be removed unless you find them unsightly or if they become inflamed. In that case, your health insurance may cover the cost of removal and biopsy. Skin lesions that are large, rapidly changing in size, or painful should be examined by a doctor.

How to deal with an epidermoid cyst

While it is tempting to squeeze the cyst, the sac will most likely refill. “To deal with the cyst permanently, it must be surgically removed,” Kroshinsky says.

After applying a local anesthetic, your doctor will use a scalpel to cut around the sac and take it out. Alternatively, for uncomplicated cysts, a minimal incision technique can be used to make a small cut or punch hole in the skin.

Pressure is then applied to the cyst to drain it, after which the sac wall is extracted through the incision; this technique produces less scarring than the standard full excision technique.

In either case, to close the incision you will need stitches, which will typically need to be removed within four to 14 days.