Epidermoid cyst signs and symptoms include:

• A small, round bump under the skin, often on the face, neck or trunk
• A tiny blackhead plugging the central opening of the cyst
• A thick, smelly, cheesy substance that leaks from the cyst
• An inflamed or infected bump

When to see a doctor

Most epidermoid cysts don't cause problems or need treatment. See your healthcare professional if you have a cyst that:

• Grows or multiplies rapidly.
• Breaks open.
• Is painful or infected.
• Is in a spot that keeps getting scratched or bumped.
• Bothers you because of how it looks.
• Is in an unusual spot, such as a finger or toe.

The surface of the skin, also called the epidermis, is made up of a thin, protective layer of cells that the body sheds nonstop. Most epidermoid cysts form when these cells move deeper into the skin rather than shed. Sometimes this type of cyst forms due to irritation or injury of the skin or a hair follicle.

Epidermal cells form the walls of the cyst and then secrete the protein keratin into it. Keratin is the thick, cheesy substance that can leak from the cyst.

Anyone can develop an epidermoid cyst, but these factors make it more likely:

• Being past puberty.
• Having a rare, inherited condition called Gardner syndrome.
• Injuring the skin.

Potential complications of epidermoid cysts include:

• Inflammation. An epidermoid cyst can become painful and swollen, even if it's not infected. An inflamed cyst is hard to remove. Your doctor is likely to postpone removing a cyst until the inflammation subsides.
• Rupture. A cyst that breaks open can lead to a boil-like infection that needs prompt treatment.
• Skin cancer. In rare cases, epidermoid cysts can lead to skin cancer.

Your healthcare professional will likely be able to tell whether your bump is an epidermoid cyst by checking the affected skin. A sample of your skin might be scraped off for study in a laboratory.

Epidermoid cysts look like sebaceous cysts or pilar cysts, but they're different. True epidermoid cysts result from damage to hair follicles or the outer layer of skin, called the epidermis. Sebaceous cysts are less common and arise from the glands that secrete oily matter that lubricates hair and skin, also called sebaceous glands. Pilar cysts develop from the root of hair follicles and are common on the scalp.

You can usually leave a cyst alone if it isn't painful or embarrassing. If you seek treatment, talk with your healthcare professional about these options:

• Injection. Injecting a steroid into the cyst can ease swelling and inflammation.
• Incision and drainage. With this method, your healthcare professional makes a small cut in the cyst and gently squeezes out the contents. This is a quick and easy method that eases symptoms. But cysts might recur after this treatment.

• Minor surgery. Your healthcare professional removes the entire cyst. You may need to return to the clinic to have stitches removed. Or your healthcare professional might use absorbable stitches, which don't need to be removed. This procedure is safe and effective and often prevents the cyst from regrowing. But it may leave a scar.

  If the cyst is inflamed, your surgery may be delayed.

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

You'll probably first visit your primary healthcare professional for diagnosis and treatment options. You may then 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 medicines, vitamins and supplements you take.
• Note any recent injuries to your skin, including surgical cuts 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 healthcare professional.

Below are some basic questions to ask your healthcare professional about epidermoid cysts. If other 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 suggest, 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 healthcare professional is likely to ask you a few 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 cysts?

What you can do in the meantime

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