How to Spot and Treat Epidermoid Cysts

What They Look Like and When to Get Them Removed

Updated on August 30, 2021

Medically reviewed by

An epidermoid cyst is the most common type of skin cyst. These types of cysts can occur anywhere on the body but tend to occur more frequently on the face or upper trunk. Other names for an epidermoid cyst include epidermal cyst, infundibular cyst, epidermal inclusion cyst, keratin cyst, and sebaceous cyst.

Find out more about what epidermoid cysts look like, whether they cause health problems, and how (and when) they are treated.

when to remove epidermoid cyst — Verywell / Brianna Gilmartin

Epidermoid Cyst Symptoms

An epidermoid cyst has a cyst wall that is made of skin cells that are found in the epidermis, the outermost layer of the skin. This cyst wall is like a balloon that projects down into the second layer of the skin, the dermis. This balloon, or cyst wall, makes keratin—a protein that's found in skin, hair, and nails and is white, cheesy, or firm.

A typical epidermoid cyst looks like a raised, round bump. If you touch it, you can typically feel the cyst wall and move the cyst around under the skin fairly easily. Often there is a small opening on the surface of the skin that may look like a scab, but that opening may be so small that it's difficult to see.

Epidermoid Cyst Rupture

Epidermoid cysts usually don't cause problems unless they get very large or the cyst wall ruptures, exposing the inside keratin to the surrounding tissue. This is a problem because the contents of a cyst are very irritating to the tissue around it. A ruptured cyst can get red, swollen, and painful. If this happens, it's best to see your healthcare provider.

Treatment

Sometimes an inflamed cyst needs to be opened to let it drain; if so, your healthcare provider may recommend treating it with warm compresses for a few days to help the cyst continue to drain. Other times, in lieu of opening the cyst, treatment may involve antibiotics or an injection with a corticosteroid (usually triamcinolone).

Surgical Removal

An epidermoid cyst doesn't have to be removed if it's small, doesn't hurt, and hasn't gotten red and swollen. Healthcare providers typically recommend the removal of a cyst to patients for the following reasons:

It's in a place where it gets irritated, rubbing against clothing or jewelry.
It's located in a place that is visible and it's getting larger quickly.
It frequently gets inflamed or infected.

If an epidermoid cyst needs to be removed, it's important that the whole cyst wall is taken out. Remember, it's the cyst wall that makes the keratin contents. If the cyst is merely opened and its contents are drained, the cyst wall remains inside the skin and will start making more keratin, causing the cyst to return.

An epidermoid cyst is usually removed by making an incision over the cyst and removing most of its contents. Then, the whole cyst wall is separated from the surrounding tissue and removed. If the incision is large enough, it may need to be sutured closed.

Frequently Asked Questions

What is an epidermoid cyst?

Epidermoid cysts, also known as epidermal inclusion cysts, are benign, slow-growing bumps beneath the skin. They are usually found in areas where there is more hair, such as the face, scalp, back of the neck, trunk, groin, and upper back.
What do epidermoid cysts look like?

Epidermoid cysts can range from less than a half-inch to several inches in size, often with an enlarged pore in the center of the bump. They may be painful or not. If infected, an epidermoid cyst can become red and inflamed, and, in some cases, even form an abscess that can rupture.
What causes an epidermoid cyst?

An epidermoid cyst is caused when cells of the outer layer of skin (called the epidermis) get trapped in the lower layer of skin (called the dermis) and continue to grow without being shed. Skin trauma, surgery, or body piercing can cause this to occur. Epidermoid cysts can also sometimes occur with rare genetic disorders like pachyonychia congenita.

Learn More: Understanding the Anatomy of the Skin
How is an epidermoid cyst diagnosed?

Because epidermoid cysts are so common—and account for the majority of skin cysts seen by dermatologists—they can often be diagnosed by their appearance alone. If needed, an in-office biopsy can be performed and reviewed by a pathologist. Under the microscope, the epithelial cells will look clumped, fibrous, and cornified (horn-like).
How do you treat an epidermoid cyst?

Since epidermoid cysts generally pose no health concerns, many are left untreated. If there is an infection, antibiotics may be prescribed; abscesses may require drainage. If you want to get rid of the cyst for cosmetic or other reasons, it can be removed surgically.
What else could an epidermoid cyst be?
Depending on its location on the body, the differential diagnosis of an epidermoid cyst may include:
Learn More: 20 Types of Skin Lesions