Epidermoid cyst

They are usually painless, slow-growing, freely movable lumps; however, sometimes a cyst will become inflamed and tender. They usually form around a hair follicle, but can sometimes be triggered by skin trauma.


Image credit: DermNet NZ

Most epidermoid cysts are small, non-painful lumps just beneath the skin. Sometimes they can grow very large over a number of years. At times, they can become infected. In this case, the lump becomes red and painful and you may need to see your doctor.

If there is uncertainty about what a lump is, you should see your doctor.

In most cases, your doctor can diagnose this type of cyst by simply examining your skin. They tend to have a typical appearance including a small central point or opening. They sometimes contain a cheesy thick material that can be squeezed out through this tiny opening. However, a key feature of an epidermoid cyst is a layer of skin surrounding the cheesy material (called a capsule) which needs to be removed fully to prevent it reforming.

Occasionally, a biopsy may be needed to rule out other conditions. If you have multiple cysts, it may be a sign of other treatable conditions, eg, cystic acne, Gardner syndrome, Steatocystoma multiplex or other types of cysts.

Apps reviewed by Healthify

You may find it useful to look at the DermDiag app.

Epidermoid cysts aren't dangerous and, once the diagnosis has been confirmed, they can often be left alone. If they become red or swollen, you can try placing a warm moist cloth (compress) over the area.

Your doctor may be able to help if the cyst is painful or if there are cosmetic concerns. In these cases they may:

• Inject an inflamed cyst with a steroid medicine to reduce swelling.
• Drain the cyst with a small surgical incision. This is usually done is an abscess forms and may be combined with antibiotic treatment.
• Surgically remove large cysts, ones that are in an awkward position or cysts that keep getting infected.