Pilar cysts grow around hair follicles and usually appear on the scalp. They are often harmless and may disappear on their own.

A cyst is a small lump filled with fluid. They form under the skin. Cysts are very common and usually have no symptoms or side effects.

There are several different names for a pilar cyst, including:

  • a wen
  • a trichilemmal cyst
  • an isthmus-catagen cyst

There are three main types of cysts: epidermoid, meibomian (chalazion), and pilar cysts. Pilar cysts occur in only about 10% of the population.

Many pilar cysts heal without treatment if a person is careful not to damage the skin. A surgeon is usually able to remove a cyst easily. However, sometimes even after removal, the cyst may reappear.

A cyst will appear as a small, round, or dome-shaped bump. Some pilar cysts are yellow or white. Pilar cysts tend to be between 0.5 and 5 centimeters (cm). Because they grow very slowly, a person may not notice a pilar cyst until it reaches a certain size.

Pilar cysts can be identified by their location, which is usually on the scalp. They develop around hair follicles. A follicle is a collection of cells that form a tube, or sheath, around a single hair.

Because most of the body’s hair is on the head, 90% of pilar cysts grow on the scalp. No hair usually grows on the lump formed by the cyst, which may make it easier to spot.

This type of cyst also does not have a dark point in its center. The skin covering a pilar cyst is less fragile than that of an epidermoid cyst.

A doctor can also recognize a pillar cyst easily under a microscope. An epidermoid cyst would be coated with skin cells, and a pilar cyst would be coated with keratin, which is the protein found in skin and hair cells.

A person is likely to develop more than one pilar cyst at a time.

What do pilar cysts feel like?

A pillar cyst will feel firm to the touch. Because a cyst is filled with fluid, it may move slightly when pressed. Pressing a cyst too hard can cause pain or soreness.

If a cyst is infected, it may become red and tender.

The skin covering a pilar cyst is quite thick, making it less likely to break or pop. However, cysts on the scalp are often caught with a brush or comb. This can break the skin, and pus may leak from the cyst.

Keratin helps to keep skin and hair strong and flexible. Keratin cells usually move to the surface of the skin when they die, and they either drop off or are washed away.

If instead, these cells move deeper into the skin, they can multiply and form a pilar cyst. The keratin in a cyst resembles a thick white or yellow paste.

Pilar cysts can run in families. If a parent is affected, there is a 1 in 2 chance that a child will have the condition.

Pilar cysts also tend to be more common in women than in men. They can affect people of all ethnicities and racial groups and often usually occur in middle-aged adults.

There are no apparent risk factors for pilar cysts. However, a person with damaged hair follicles or injured skin may be more likely to develop them.

Complications from a pilar cyst are rare. However, they can include:

  • Infection. If bacteria get into the cyst, the cyst can become infected. If the infection is not treated, it can progress beyond the initial cyst into the tissue and bone.
  • Tumor. Very rarely, a pilar cyst will develop into a tumor called a proliferating trichilemmal cyst. This only happens in about 3% of pilar cyst cases. The cells of the cyst multiply and the lump grows and may ulcerate. These tumors grow slowly and are not usually cancerous.
  • Recurrence. After removal, a scar will form. However, the cyst may grow back.

A doctor or dermatologist should check any lumps or bumps on the skin. Cysts are usually not a cause for concern. However, getting the right diagnosis is essential.

A doctor or dermatologist will carefully examine the cyst. They may ask about medical history and additional symptoms.

A doctor may opt to use a CT or MRI scan to see if the cyst has reached the deeper soft tissue or the bone.

If a doctor cannot visually classify a cyst, they may have to remove it and examine it under a microscope to ensure it is not harmful.

Cysts often heal on their own. Holding a clean, warm washcloth to a cyst can reduce swelling and help it to heal.

A doctor will usually prescribe antibiotics to treat an infected pilar cyst.

It is not always necessary to remove a cyst. If the cyst is not causing any symptoms, a person may decide not to seek treatment.

Removal

Since pilar cysts usually form on the scalp, catching one when dressing or brushing the hair can be painful. If a cyst is causing discomfort, a person can have it removed.

A person will receive a local anesthetic before a cyst is removed. There are two methods of removal:

  • making a small cut in the skin to drain the cyst of fluid
  • removing the entire cyst without cutting into it

The procedure is usually quick, and it does not require an overnight stay in a hospital or clinic.

A doctor will usually apply a dressing after removing the cyst. It is usually good to avoid getting the dressing wet and take care when touching the affected area.

Pilar cysts usually form around the hair follicles on the scalp. They are not contagious and are usually harmless. They can cause pain or discomfort when infected. In this case, a doctor will often prescribe medication.

In rare cases, they may develop into a tumor. However, it is usually not cancerous. A person may have more than one pilar cyst at a time, and they may disappear and return. In most cases, a cyst will cause no symptoms and will heal without treatment.

If necessary, a doctor will remove a cyst with a simple procedure. The cyst may reappear in the same location, and new cysts may develop in the future.

Can you pop a pilar cyst?

A person should try to avoid scratching, popping, or picking at a cyst. Doing so can cause the area to become infected.

Before touching the area, a person should always wash their hands. If a person wants to have their cyst removed, they should have a doctor do the procedure.

Can pillar cysts cause cancer?

In extremely rare cases, a proliferating trichilemmal cyst can become cancerous. A person who is concerned may wish to have their cyst evaluated.

How do you prevent a pilar cyst?

It is not possible to prevent a pilar cyst. It may be possible to prevent its reoccurrence after surgery. The cyst is less likely to grow back if the doctor has removed the cyst entirely, rather than just draining it.