Epidermal cyst

Also known as sebaceous cyst, carbuncle cyst or keratin cyst

Epidermal cysts are small cysts or lumps that develop just under the skin and are usually found on the face, neck or back.

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.

Symptoms

Most sebaceous 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.

Diagnosis

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 punctum. Sometimes, a cheesy thick material can be squeezed out through this tiny opening. Occasionally, a biopsy may be needed to rule out other conditions.

Treatment

Epidermal cysts are not dangerous and once confirmed that is what it is, can often be left alone. If they become red or swollen, you can try placing a warm moist cloth (compress) over the area.

  • Injecting an inflamed cyst with a steroid medicine that reduces swelling.
  • Draining via a small surgical incision if an abscess forms.
  • Surgical removal of large cysts, ones that are in an awkward position or cysts that keep getting infected.

Learn more

Epidermoid and pilar cysts Patient (UK)

Images of cysts DermNet (NZ), 2014

Credits: Habif TP, ed. Clinical Dermatology. 5th ed. Philadelphia, Pa: Mosby Elsevier; 2009.