Overview

Epidermoid (ep-ih-DUR-moid) cysts are noncancerous small bumps beneath the skin. They can appear anywhere on the skin, but are most common on the face, neck and trunk.

Epidermoid cysts are slow growing and often painless, so they rarely cause problems or need treatment. You might choose to have a cyst removed by a doctor if its appearance bothers you or if it's painful, ruptured or infected.

Many people refer to epidermoid cysts as sebaceous cysts, but they're different. True sebaceous cysts are less common. They arise from the glands that secrete oily matter that lubricates hair and skin (sebaceous glands).

Symptoms

Epidermoid cyst signs and symptoms include:

• A small, round bump under the skin, usually on the face, neck or trunk
• A tiny blackhead plugging the central opening of the cyst
• A thick, yellow, smelly material that sometimes drains from the cyst
• Redness, swelling and tenderness in the area, if inflamed or infected

When to see a doctor

Most epidermoid cysts don't cause problems or need treatment. See your doctor if you have one or more that:

• Grows rapidly
• Ruptures or becomes painful or infected
• Occurs in a spot that's constantly irritated
• Bothers you for cosmetic reasons
• Is in an unusual location, such as a finger and toe

Causes

The surface of your skin (epidermis) is made up of a thin, protective layer of cells that your body continuously sheds. Most epidermoid cysts form when these cells move deeper into your skin and multiply rather than slough off. Sometimes the cysts form due to irritation or injury of the skin or the most superficial portion of a hair follicle.

The epidermal cells form the walls of the cyst and then secrete the protein keratin into the interior. The keratin is the thick, yellow substance that sometimes drains from the cyst. This abnormal growth of cells may be due to a damaged hair follicle or oil gland in your skin.

Many people refer to epidermoid cysts as sebaceous cysts, but they're different. True sebaceous cysts are less common. They arise from the glands that secrete oily matter that lubricates hair and skin (sebaceous glands).

Risk factors

Nearly anyone can develop one or more epidermoid cysts, but these factors make you more susceptible:

• Being past puberty
• Having certain rare genetic disorders
• Injuring the skin

Complications

Potential complications of epidermoid cysts include:

• Inflammation. An epidermoid cyst can become tender and swollen, even if it's not infected. An inflamed cyst is difficult to remove. Your doctor is likely to postpone removing it until the inflammation subsides.
• Rupture. A ruptured cyst often leads to a boil-like infection that requires prompt treatment.
• Infection. Cysts can become infected and painful (abscessed).
• Skin cancer. In very rare cases, epidermoid cysts can lead to skin cancer.

Diagnosis

Doctors can usually make a diagnosis by looking at the cyst. Your doctor may also scrape off skin cells and examine them under a microscope or take a skin sample (biopsy) for detailed analysis in the laboratory.

Epidermoid cysts look like sebaceous cysts, but they're different. True epidermoid cysts result from damage to hair follicles or the outer layer of skin (epidermis).

Treatment

You can usually leave a cyst alone if it doesn't cause discomfort or cosmetic problems. If you seek treatment, talk with your doctor about these options:

• Injection. This treatment involves injecting the cyst with a medicine that reduces swelling and inflammation.
• Incision and drainage. With this method, your doctor makes a small cut in the cyst and gently squeezes out the contents. This is a fairly quick and easy method, but cysts often recur after this treatment.
• Minor surgery. Your doctor can remove the entire cyst. You may need to return to the doctor's office to have stitches removed. Minor surgery is safe and effective and usually prevents cysts from recurring. If your cyst is inflamed, your doctor may delay the surgery.

Lifestyle and home remedies

You can't stop epidermoid cysts from forming. But you can help prevent scarring and infection by:

• Not squeezing a cyst yourself
• Placing a warm, moist cloth over the area to help the cyst drain and heal

Preparing for an appointment

You'll probably first visit your primary care doctor. He or she will diagnose your condition and outline treatment for your cyst. Options may include observation, incision and drainage if it is inflamed or infected, and removal. Occasionally, you may be referred to a doctor who specializes in skin disorders (dermatologist).

Here's some information to help you get ready for your appointment.

What you can do

• List your key medical information, such as conditions you've been treated for and medications, vitamins and supplements you take.
• Note any recent injuries to your skin, including surgical incisions and accidental wounds.
• List questions you have about your condition. Having a list of questions can help you make the most of your time with your doctor.

Below are some basic questions to ask your doctor about epidermoid cysts. If any additional questions occur to you during your visit, don't hesitate to ask.

• Do I have an epidermoid cyst?
• What causes this type of cyst?
• Is the cyst infected?
• What treatment do you recommend, if any?
• Will I have a scar after treatment?
• Am I at risk of this condition recurring?
• Can I do anything to help prevent a recurrence?
• Do epidermoid cysts increase my risk of other health problems?

What to expect from your doctor

Your doctor is likely to ask you a number of questions, such as:

• When did you notice this skin growth?
• Have you noticed any other skin growths?
• Have you had similar growths in the past? If so, on what parts of your body?
• Have you had severe acne?
• Is the growth causing any discomfort?
• Are you embarrassed by the growth?
• Have you had any recent skin injuries, including minor scrapes?
• Have you recently had a surgical procedure in the affected area?
• Does anyone in your family have a history of acne or multiple cysts?

What you can do in the meantime

Resist the urge to try to squeeze or "pop" your cyst. Your doctor will be able to take care of the cyst with the least risk of scarring and infection.