Pilar cysts are non-cancerous, slow-growing masses that commonly form just beneath the skin’s surface, particularly on the scalp. These lumps often appear as multiple lesions. Understanding the nature of these common skin growths can guide decisions about when professional medical evaluation is appropriate. Though typically harmless, pilar cysts may require treatment if they become symptomatic or bothersome.
Defining Pilar Cysts on the Scalp
Pilar cysts, also known as trichilemmal cysts, are small, firm sacs that originate from the outer root sheath of a hair follicle. Approximately 90% of these cysts develop on the scalp, which has the highest concentration of hair follicles. The cyst itself is a smooth, dome-shaped nodule that is often mobile beneath the skin’s surface.
The contents of a pilar cyst are primarily composed of keratin, a tough protein found in hair, skin, and nails, along with cellular debris. This material is typically thick and paste-like, often appearing white or yellowish if the cyst is ruptured. Unlike some other types of cysts, pilar cysts have a thick wall, which makes them less prone to spontaneous rupture. They can range in size from a few millimeters to several centimeters, growing gradually over time.
Understanding the Causes and Risk Factors
The formation of multiple pilar cysts is strongly linked to a genetic predisposition rather than environmental factors. These cysts often run in families, following an autosomal dominant inheritance pattern. This means a person has a roughly 50% chance of developing them if one parent has the tendency.
Pilar cysts occur in about 5% to 10% of the population. They form when cells from the outer layer of the hair root sheath multiply and move deeper into the skin, creating a sac where keratin builds up. They are most frequently observed in middle-aged women, though they can affect people of any age or gender.
When to See a Doctor
Pilar cysts are benign and rarely lead to significant health complications. A dermatologist can usually diagnose a pilar cyst through a visual and physical examination. However, a biopsy may be performed to confirm the diagnosis or rule out other types of scalp masses.
Immediate evaluation is necessary if the cyst shows signs of inflammation or infection, such as rapid growth, increased pain, or tenderness. Other concerning signs include the area becoming red or warm to the touch. The presence of thick fluid, pus, or a foul odor oozing from the cyst indicates an active infection that requires prompt treatment.
Removal and Treatment Options
Treatment is not always required for pilar cysts, but removal may be recommended for cosmetic reasons, physical discomfort, or if the cyst has become infected or ruptured. The definitive treatment for preventing recurrence is the complete surgical excision of the cyst, including its entire sac wall. This minor procedure is typically performed in a doctor’s office under local anesthesia.
A traditional surgical excision involves making an incision over the cyst, carefully dissecting and removing the capsule, and then closing the wound with sutures. A less invasive technique often used for scalp cysts is the punch biopsy method, which utilizes a small circular instrument to create a tiny opening. This method allows the contents to be expressed and the cyst wall to be extracted through the smaller incision.
The punch method is often preferred for minimizing scarring and promoting quicker healing times on the scalp. If a cyst is acutely infected, a healthcare provider may first prescribe oral antibiotics to reduce inflammation before proceeding with surgical removal.