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What Is a Pilar Cyst on the Scalp?

Medically Reviewed by Dan Brennan, MD on April 13, 2021

A pilar cyst, sometimes called epidermoid cysts, occurs when a hair follicle gets clogged. They can happen anywhere on your body but are most common the scalp. Pilar cysts can be irritating, but are usually not dangerous to your health.

What Causes a Pilar Cyst

Pilar cysts of the scalp are slow-growing, painless cysts. They form in blocked hair follicles and get larger with time. Since you have hair follicles all over your body, you may also find pilar cysts on your face, neck, chest, stomach, and back. They are more common on the scalp because of the oils your scalp secretes to nourish hair.

Pilar cysts begin when the outer layer of skin, the epidermis, sheds old skin cells. These shedding cells can sometimes shift under the surface of your skin instead of falling off. When this happens, the shedded cells start multiplying as if they are still growing. Instead of moving up to the surface, they stay trapped under your skin and begin to build up.‌

Meanwhile, your scalp produces keratin, which is secreted to maintain hair health. The keratin also builds up with the dead skin cells under your epidermis. This is the white-yellow liquid that you may see oozing from your cyst if it ruptures.

Diagnosing a Pilar Cyst

Pilar cysts can sometimes be diagnosed by your doctor with a simple visual examination. However, pilar cysts can look like other skin conditions, so your doctor will need to rule out other health concerns. They will ask you questions about your symptoms and, if necessary, may take a biopsy of the pilar cyst to look at under a microscope.

Treating a Pilar Cyst on the Scalp

Self-healing. A pilar cyst on your scalp may go away on its own over time. Keep in mind that just as the cyst is slow-growing, it is also slow to shrink back down. This is especially true if it is large and there is a lot of fluid needing to drain out.

If you don’t want to wait and see if the pilar cyst on your scalp shrinks, you can talk to your doctor about more active treatment options.

Cyst removal. While generally not harmful, pilar cysts can be irritating and cause pain when brushing hair. Pilar cysts can be removed by your doctor with a simple outpatient surgery that involves cutting open the cyst, draining the fluid, and removing the cyst wall so it doesn’t return again.

Pilar Cyst Concerns

Not preventable. Doctors have not identified a way to prevent cysts from forming. There isn’t a way to predict when or where a pilar cyst of the scalp may form. 

Benign, but can be irritating. Pilar cysts on the scalp are not cancerous and usually don’t have negative effects on your overall health. While most pilar cysts are painless, some cysts may be irritated if you bump or scratch them. Being located on your scalp, it is easy to brush or comb your pilar cyst without realizing it.

Possibility of infection. Pilar cysts on your scalp can cause problems if they rupture and become infected. If this happens, bacteria may enter your bloodstream through the wound opening and cause other symptoms similar to an illness. Infections may require a topical or oral antibiotic, and can become serious without medical attention. Signs that your pilar cyst is infected include:

  • Pain in or around the cyst
  • Thick fluid oozing from the cyst
  • A bad smell coming from the oozing liquid‌
  • Inflammation, redness, or swelling‌

If you have any of these symptoms, talk to your doctor right away.

To prevent infection and potential scarring, avoid:

  • Squeezing the cyst
  • Attempting to “pop” it and drain the liquid
  • Sticking a needle in it
  • Cutting it open by yourself to remove the cyst
WebMD Medical Reference

Sources

SOURCES:

‌Cedars Sinai: “Epidermoid Cysts of the Skin.”

‌Cincinnati Children’s Hospital: “Types of Cysts.”

‌Mayo Clinic: “Epidermoid cysts.”

‌Skin Support: “Epidermoid and pilar cysts.”

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