Proliferating trichilemmal cysts (also known as pilar cysts) are benign cysts that form from the outer root sheath of the hair follicle. They are most commonly found on the scalp, but can also occur on other parts of the body. They are usually round, firm, and filled with keratin. They are usually painless, but can become tender or painful if they become infected. Treatment is usually not necessary, but they can be surgically removed if desired.

The most common symptom of a proliferating trichilemmal cyst is a small, firm, dome-shaped bump on the scalp. The bump may be skin-colored, pink, or yellowish. It may be tender to the touch and may be filled with a thick, yellowish material. Other symptoms may include itching, burning, or pain.

Proliferating trichilemmal cysts are caused by a genetic mutation in the gene that controls the growth of the outer layer of the skin (the epidermis). This mutation causes the cells in the epidermis to divide and grow abnormally, forming a cyst. The exact cause of this mutation is unknown, but it is believed to be inherited.

The treatment for proliferating trichilemmal cyst is typically surgical excision. This involves removing the cyst and any surrounding tissue. In some cases, a biopsy may be performed to confirm the diagnosis. In some cases, a topical steroid cream may be prescribed to reduce inflammation and itching. In rare cases, radiation therapy may be used to shrink the cyst.

1. Exposure to ultraviolet radiation
2. Genetic predisposition
3. Female gender
4. Older age
5. History of trauma or inflammation to the scalp

Proliferating trichilemmal cysts are benign and usually do not require treatment. However, if the cyst is causing discomfort or is cosmetically undesirable, it can be surgically removed. In some cases, medications such as topical corticosteroids may be used to reduce inflammation and itching.