Pilar cysts (trichilemmal cysts) are common, non-cancerous skin growths originating from the root sheath of a hair follicle. They are the most frequent type of skin cyst found on the head, occurring in less than 10% of the population. Although generally harmless, they can increase in size, leading to discomfort, infection, or cosmetic concern, often prompting professional intervention.
Identifying Pilar Cysts
Pilar cysts typically manifest as smooth, firm, and mobile lumps beneath the skin’s surface. Approximately 90% develop on the scalp, though they can appear on other hair-bearing areas. They range from 0.5 to 5 centimeters in diameter, often starting small and growing slowly. The overlying skin usually appears normal, and unlike some other cysts, pilar cysts lack a visible central pore.
The cyst contents consist of keratin, a protein that often presents as a thick, cheese-like material. These cysts arise when the outer root sheath of the hair follicle becomes obstructed, causing keratin to accumulate and form a sac. A genetic predisposition is common, with pilar cysts frequently running in families and sometimes leading to multiple lesions.
Management Without Surgery
For small, asymptomatic pilar cysts, watchful waiting is often appropriate, as they may remain stable or grow slowly. However, these cysts rarely resolve on their own because the keratin-producing cyst wall remains intact under the skin. If the cyst becomes painful, inflamed, or infected, a medical professional may prescribe oral antibiotics to manage the infection. Inflammation must typically subside before surgical removal can be safely performed.
Avoid attempting to drain, squeeze, or pierce a pilar cyst at home. Self-treatment significantly increases the risk of introducing bacteria, potentially leading to a painful abscess. Draining the cyst at home is unlikely to remove the entire sac lining, meaning the cyst will almost certainly regrow. Improper manipulation can also cause the cyst contents to rupture, triggering a foreign-body reaction and increased inflammation.
Medical Removal Procedures
Surgical excision is the definitive method for permanently removing a pilar cyst, ensuring the entire growth is removed and preventing recurrence. Removal is generally elective, based on patient preference, but is necessary if the cyst is infected, ruptures, or causes significant pain or obstruction. The procedure is typically performed in an outpatient setting using a local anesthetic.
The standard approach involves making a precise incision over the cyst and carefully dissecting the entire capsule (sac) from the surrounding tissue. Complete removal of the cyst wall is necessary, as leaving any fragment behind can cause the cyst to regrow. For large or previously infected cysts, a traditional elliptical excision may be used to ensure adequate margins and removal of scar tissue.
For cysts that are not excessively large, a minimal incision technique offers a better cosmetic outcome. This involves making a very small incision, often just a few millimeters, through which the cyst contents are expressed. The surgeon then extracts the collapsed cyst sac through the opening. Another option for smaller lesions is punch excision, where a circular tool removes a core of skin containing the entire cyst. Both minimal techniques result in smaller scars and potentially faster healing times.
Recovery and Recurrence Prevention
Following professional removal, recovery requires simple wound care to ensure optimal healing. Patients are instructed to keep the surgical site clean and dry for the first 24 to 48 hours. Afterward, the area should be gently washed with mild soap and water, and a fresh dressing applied daily or as directed.
Mild discomfort and swelling are common initially and can be managed with over-the-counter pain relievers. Patients should avoid strenuous activities that strain the surgical area for one to two weeks, especially for cysts removed from the scalp. If non-dissolvable sutures were used, a clinician will need to remove them seven to fourteen days after the operation.
The most effective measure for recurrence prevention is the complete surgical removal of the cyst wall, which eliminates the source of keratin production. If the entire sac is successfully excised, the likelihood of the cyst returning is very low. Patients should monitor the area for signs of infection, such as increasing redness, swelling, warmth, or discharge, and seek follow-up care if unusual symptoms develop.