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.

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.

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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.

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.