What is an epidermoid cyst?

Epidermoid cysts are also known as epidermal inclusion cysts. They are benign, slow-growing bumps beneath the skin. They are usually found in areas where there is more hair, such as: Face Scalp Back of the neck Trunk Groin Upper back

What do epidermoid cysts look like?

Epidermoid cysts can range from less than a half-inch to several inches in size. There is often 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. In some cases, they may form an abscess that can rupture.

What causes an epidermoid cyst?

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

How is an epidermoid cyst diagnosed?

Epidermoid cysts are common. They account for the majority of skin cysts seen by dermatologists . Because of this, 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 cells will look clumped, fibrous, and horn-like.

How do you treat an epidermoid cyst?

Epidermoid cysts generally pose no health concerns. This is why many are left untreated. If there is an infection, antibiotics may be prescribed. Abscesses may need to be drained . If you want to get rid of the cyst for cosmetic or other reasons, it can be removed surgically.

What could an epidermoid cyst be mistaken for?

Your healthcare provider may use differential diagnosis to confirm that you have an epidermoid cyst. This means other causes will need to be excluded, such as: Acne Sebaceous cyst Furuncle/boil Lipoma Milia Sebaceous hyperplasia

How to Spot and Treat Epidermoid Cysts

An epidermoid cyst is the most common type of skin cyst. They are benign (noncancerous).

They tend to occur more frequently on the face or upper trunk. They can occur anywhere on the body, though.

Other names include:

Epidermal cyst
Infundibular cyst
Epidermal inclusion cyst
Keratin cyst

The terms epidermoid cyst and sebaceous cyst are often used interchangeably, but this isn't correct. They are different types of cysts with different contents.

This article discusses epidermoid cysts and their appearance. It also looks at whether they cause health problems, and how and when they are treated.

when to remove epidermoid cyst — Verywell / Brianna Gilmartin

Epidermoid Cyst Symptoms

The wall of an epidermoid cyst is made of skin cells that are found in the epidermis. This is the outermost layer of the skin.

The cyst wall is like a balloon that extends down into the dermis. The dermis is the second layer of skin.

The cyst wall makes keratin, a protein found in skin, hair, and nails. The keratin is white, cheesy, or firm.

A typical epidermoid cyst looks like a raised, round bump. You can usually feel the cyst wall when you touch it. You will probably be able to move the cyst around under the skin fairly easily.

There is often a small opening on the surface of the skin. It may look like a scab, but may be so small that it's hard to see.

Recap

An epidermoid cyst is a balloon-like structure filled with keratin. It looks like a round, raised bump.

Epidermoid Cyst Rupture

Small epidermoid cysts don't usually cause problems. Very large cysts may need to be treated.

If the cyst wall ruptures, it will expose surrounding tissue to the keratin inside. This is a problem because the contents can be very irritating.

A ruptured cyst can become red, swollen, and painful. If this happens, it's best to see your doctor.

Treatment of an Epidermoid Cyst

Sometimes an inflamed cyst needs to be opened to let it drain. When this happens, your doctor may recommend using warm compresses for a few days to help it continue to drain.

In some cases, your doctor may not open the cyst. Instead, treatment may involve antibiotics or an injection with a corticosteroid (usually triamcinolone).

Surgical Removal of an Epidermoid Cyst

An epidermoid cyst doesn't have to be removed if:

It's small
It doesn't hurt
It's not red and swollen

Your doctor may recommend removing your cyst if:

It's in a place where it gets irritated. For example, it may rub against clothing or jewelry.
It's in a visible spot and it's getting larger quickly.
It frequently gets inflamed or infected.

When an epidermoid cyst is removed, the whole cyst wall needs to be taken out. This is because it's the cyst wall that makes the keratin contents.

If the cyst is just drained but the cyst wall remains, it will start making more keratin. This will cause the cyst to return.

To remove the cyst, your healthcare provider will make an incision and remove most of the contents. Then, your healthcare provider will separate the cyst wall from the surrounding tissue and remove it. If the incision is large, it may need to be stitched closed.

Recap

An inflamed cyst may be drained and treated with warm compresses or antibiotics. A corticosteroid injection may also help. If a cyst becomes large or irritating, it can be surgically removed.

Summary

An epidermoid cyst is a common, benign cyst filled with keratin. Small cysts usually don't need to be treated.

Sometimes a cyst will grow very large or rupture. Inflamed cysts may be drained. Treatment can include warm compresses, antibiotics, or a corticosteroid injection.

You may want your cyst removed for cosmetic reasons, or because it is large or irritating. To remove the cyst, your doctor will first drain it and then remove the cyst wall.

Frequently Asked Questions

What is an epidermoid cyst?
Epidermoid cysts are also known as epidermal inclusion cysts. They are benign, slow-growing bumps beneath the skin. They are usually found in areas where there is more hair, such as:
- Face
- Scalp
- Back of the neck
- Trunk
- Groin
- Upper back
What do epidermoid cysts look like?

Epidermoid cysts can range from less than a half-inch to several inches in size. There is often 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. In some cases, they may form an abscess that can rupture.
What causes an epidermoid cyst?

An epidermoid cyst forms when cells of the outer layer of skin get trapped in the lower layer of skin and continue to grow without being shed. Skin trauma, surgery, or body piercing can cause this. 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?

Epidermoid cysts are common. They account for the majority of skin cysts seen by dermatologists. Because of this, 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 cells will look clumped, fibrous, and horn-like.
How do you treat an epidermoid cyst?

Epidermoid cysts generally pose no health concerns. This is why many are left untreated. If there is an infection, antibiotics may be prescribed. Abscesses may need to be drained. If you want to get rid of the cyst for cosmetic or other reasons, it can be removed surgically.
What could an epidermoid cyst be mistaken for?
Your healthcare provider may use differential diagnosis to confirm that you have an epidermoid cyst. This means other causes will need to be excluded, such as:
Learn More: 20 Types of Skin Lesions