Epidermal Inclusion Cyst (Sometimes Called Sebaceous Cyst)

What is an epidermal inclusion cyst (sebaceous cyst)?

An epidermal inclusion cyst (epidermoid cyst) is a fluid-filled pocket under the surface of your skin. It looks and feels like a lump or bump on your skin.

Many people call epidermal inclusion cysts “sebaceous cysts.” The term “sebaceous cyst” is misleading because the cyst isn’t filled with sebum. Sebum is an oily substance created by your sebaceous glands that keeps your skin moist. Instead, a keratin (a protein) and cell debris fill epidermal inclusion cysts. 

Most healthcare providers only use the term “sebaceous cysts” when cysts are associated with a skin condition known as steatocystoma multiplex. Cysts that form with this condition fill with sebum, so they’re truly “sebaceous cysts.” True sebaceous cysts aren’t common, but epidermal inclusion cysts are.

As the name implies, epidermal inclusion cysts form under the top layer of your skin (epidermis).

How common are epidermal inclusion cysts (sebaceous cysts)?

Epidermal inclusion cysts are the most common type of skin cyst.

What does an epidermal inclusion cyst (sebaceous cyst) look like?

An epidermal inclusion cyst may have the following features:

• A round bump or dome-shaped lump.
• A dark dot (punctum) in the center of the cyst.
• Size ranging from .25 inches to greater than 2 inches. It can grow slowly.
• Skin discoloration (usually pink to red or darker than your natural skin tone).
• Tenderness or warmth to the touch.
• It can move easily.

What are epidermal inclusion cysts filled with?

A keratin and cell debris substance fills epidermal inclusion cysts. When drained by a dermatologist, this substance looks thick and yellow and has a foul odor.

Is an epidermal inclusion cyst painful?

An epidermal inclusion cyst isn’t usually painful. Sometimes, the cyst can inflame (swell) and feel tender when you touch it. As the cyst grows, you may experience skin irritation and pain if it ruptures (breaks open). Occasionally you’ll experience itching at the site of an epidermal inclusion cyst. See your healthcare provider if you develop pain on or near a cyst or have other concerning symptoms.

Where do epidermal inclusion cysts form?

Epidermal inclusion cysts can form anywhere on your body, but they’re most common on your:

• Face.
• Chest.
• Back.
• Scalp
• Neck.
• Legs.
• Arms.
• Genitalia.

What causes an epidermal inclusion cyst (sebaceous cyst)?

Epidermal inclusion cysts form after a blockage to a hair follicle (an opening in your skin where hair grows out) at the follicular infundibulum (the top part of the hair follicle). 

Your body naturally sheds skin cells when they reach the end of their life cycle. If you have a skin injury like a scratch, surgical wound or a skin condition like acne or chronic sun damage, it can disrupt the path your skin cells take to leave your body. This traps these cells and other components like keratin, so they collect under the surface of your skin. This is how a cyst forms.

On areas of your body where you don’t have hair follicles, a cyst can form after an injury or trauma to your skin, too. The injury pushes your skin cells below the top layer of your skin into the second layer (dermis). This creates a pocket where keratin collects and forms a cyst.

What are the risk factors for epidermal inclusion cysts?

Although they can appear at any age, epidermal inclusion cysts most frequently occur between ages 20 to 60. Epidermal inclusion cysts rarely appear before puberty. They’re more common in men than women.

Some rare genetic conditions and other conditions can lead to the development of multiple epidermal inclusion cysts, including:

• Gardner syndrome (familial adenomatous polyposis).
• Gorlin syndrome (basal cell nevus syndrome).
• Favre-Racouchot syndrome.
• Human papillomavirus (HPV).

Certain medications may increase your risk of developing epidermal inclusion cysts, including:

• BRAF inhibitors.
• Imiquimod.
• Cyclosporine.

Is an epidermal inclusion cyst contagious?

No, epidermal inclusion cysts aren’t contagious.

What are the complications of an epidermal inclusion cyst (sebaceous cyst)?

Complications of an epidermal inclusion cysts may include:

• Inflamed epidermal inclusion cyst: The cyst is swollen and tender.
• Infected epidermal inclusion cyst: Your body is fighting harmful bacteria within the cyst, which causes swelling, pain and skin discoloration.
• Ruptured epidermal inclusion cyst: The cyst breaks open, which causes swelling, pain, skin discoloration and yellow (often stinky) fluid drainage.

Is an epidermal inclusion cyst a sign of cancer?

Epidermal inclusion cysts are rarely harmful. However, researchers have found rare cases where malignancy (cancer) formed within the cyst, specifically:

• Squamous cell carcinoma.
• Basal cell carcinoma.

An epidermal inclusion cyst may be concerning if it has any of the following characteristics:

• Signs of infection, including pain, skin discoloration, swelling and/or drainage.
• A fast rate of growth.
• A diameter larger than 5 centimeters.

Talk to your healthcare provider if you notice changes to your cyst.

How is an epidermal inclusion cyst (sebaceous cyst) diagnosed?

A healthcare provider can diagnose an epidermal inclusion cyst during a physical exam simply by looking at it and learning more about your symptoms if you have any. 

Although not usually necessary, testing can confirm a diagnosis. It may include:

• Radiology or imaging tests: An ultrasound may help determine the contents of the cyst. A CT scan (computed tomography scan) can confirm the diagnosis of a large epidermal inclusion cyst and help your provider determine the best plan for removal.
• Biopsy: A provider will remove a small amount of the tissue from the cyst to examine it.

Should I see a specialist for an epidermal inclusion cyst?

If you notice changes to your skin, contact a healthcare provider. You might start with a primary care physician (PCP), and they can refer you to see a dermatologist or a doctor who specializes in skin conditions. Only certain providers can remove epidermal inclusion cysts. Your provider may refer you to a specialist trained to remove cysts, such as a dermatologist, general surgeon or plastic surgeon.

How is an epidermal inclusion cyst (sebaceous cyst) treated?

In many cases, a healthcare provider may recommend monitoring the epidermal inclusion cyst and not treating it if it doesn’t cause symptoms.

If the cyst swells and/or causes discomfort, use a warm compress over the cyst to reduce symptoms at home. If your symptoms continue or get worse, contact a provider. They may recommend removing it, or they’ll inject a steroid medication into the cyst to temporarily reduce swelling.

Antibiotics can treat an infected epidermal inclusion cyst.

Epidermal inclusion cyst (sebaceous cyst) removal

Your provider may remove the epidermal inclusion cyst with the following procedures:

• Incision and drainage: Your provider will make a small opening over the cyst and release the collection of fluid within the cyst. This procedure won’t resolve the cyst, since your provider won’t remove the cyst capsule (the outer portion of the cyst). It can help with inflammation and swelling.
• Surgical excision: A surgical procedure that removes the cyst. This procedure uses a local anesthetic (you won’t be asleep and you won’t feel pain). The removal of the capsule (the outer portion of the cyst) prevents the cyst from growing back.

Don’t try popping or draining the cyst yourself. This could cause an infection, and the cyst will likely grow back (recur).

Are there side effects of the treatment?

Risks of surgical excision of a cyst are rare but may include:

• Infection.
• Bleeding.
• Scars.
• Pain.
• Recurrence.

Can an epidermal inclusion cyst (sebaceous cyst) be prevented?

Epidermal inclusion cysts typically form randomly. However, avoiding injury or trauma to your skin and treating skin conditions may be helpful to reduce your risk.

What’s the outlook for an epidermal inclusion cyst (sebaceous cyst)?

Once you have a diagnosis, you can wait and see if the cyst improves on its own or discuss treatment options with your healthcare provider.

Most cysts don’t cause symptoms. But it can be challenging if your cyst forms on a very visible part of your body, like on your face or scalp, or if it causes pain. Talk to a healthcare provider about cyst removal if the cyst is bothersome.

Does an epidermal inclusion cyst go away?

Some cysts decrease in size, while others continue to grow until you get treatment. Without treatment, you may have the cyst for the rest of your life.

Can epidermal inclusion cysts get worse?

Epidermal inclusion cysts sometimes remain small in size and asymptomatic for several years. However, they can also increase in size and may become uncomfortable or irritated. If the cyst bothers you, discuss treatment options with your healthcare provider.

When should I see a healthcare provider?

Always see your healthcare provider if you find a lump on your skin. It might be an epidermal inclusion cyst, another type of cyst or something else. Don’t try to diagnose it yourself. See your healthcare provider for a clear diagnosis and specialized treatment.

What questions should I ask my healthcare provider?

You may want to ask your provider:

• Do I have an epidermal inclusion cyst or another type of cyst?
• Will this go away on its own, or will it need treatment?
• Do you think the epidermal inclusion cyst will get bigger?
• What treatment options do you recommend?
• Do I need to see a specialist or a surgeon?
• What should I do if the cyst comes back after the procedure?

Is an epidermal inclusion cyst (sebaceous cyst) dangerous?

Most epidermal inclusion cysts aren’t dangerous. They’re usually asymptomatic. Not all epidermal inclusion cysts become infected, but infection is possible. Infections can be dangerous if left untreated. While very rare, some cysts can turn into cancer, so contact a healthcare provider if you notice changes to your skin.