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.
A surgeon is usually able to remove a cyst easily. However, even after removal, a cyst may reappear.
Many pilar cysts heal without treatment if a person is careful not to damage the skin.
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.
These cysts 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 percent of pilar cysts grow on the scalp.
No hair usually grows on the lump formed by the cyst, and this may make it easier to spot.
The lump 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.
Pilar cysts are relatively uncommon, affecting 5 to 10 percent of the population.
There are three main types of cyst:
- Epidermoid cysts mostly affect adolescents and appear on the face, chest, shoulders, or genitals.
- Pilar cysts tend to form in adults aged 45 to 65. These cysts grow around hair follicles.
- A meibomian cyst, or chalazion, develops around the eyelid and can appear at any age.
Pilar cysts can be identified by their location, which is usually on the scalp.
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. These types of cysts are also easily distinguished using a microscope. An epidermoid cyst is coated with skin cells and a pilar cyst with keratin.
A person is likely to develop more than one pilar cyst at a time.
There are several different names for a pilar cyst, including:
- a wen
- a trichilemmal cyst
- an isthmus-catagen cyst
Keratin is a protein found in skin cells, and it 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 looks like a thick white or yellow paste.
Pilar cysts can run in families. If a parent is affected, there is a 50 percent chance that a child will have the condition.
This type of cyst is more common in women than men. They usually occur in middle-aged adults.
There are no apparent risk factors for pilar cysts, but a person with damaged hair follicles or injured skin may be more likely to develop them.
A doctor or dermatologist should check any lumps or bumps on the skin. Cysts are usually not a cause for concern, but getting the right diagnosis is essential.
A doctor or dermatologist will carefully examine the cyst. They may ask about medical history and additional symptoms.
If a doctor cannot visually classify a cyst, they may have to remove it and examine it under a microscope to ensure that 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.
If a cyst is causing discomfort, it can be removed. Because pilar cysts usually form on the scalp, catching one when dressing or brushing the hair can be painful.
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 a good idea to avoid getting the dressing wet and take care when touching the affected area.
A scar will form following a removal. The cyst may grow back, but this is less likely if the cyst has been removed entirely, rather than drained.
Pilar cysts are not contagious. They are usually harmless, but they can cause pain or discomfort when infected. In this case, a doctor will often prescribe medication.
Very rarely, a pilar cyst will develop into a pilar tumor. This happens when cells multiply, and the lump grows larger than 5 cm. These tumors grow slowly and are not usually 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 future.