Pilar cysts are common, benign lumps that form beneath the skin, most frequently on the scalp. These growths are typically firm, smooth, and movable. The most direct answer to whether pilar cysts disappear naturally is that they generally do not resolve on their own, and intervention is usually required for removal. While harmless, their persistent nature means they remain in place, often growing slowly over time, unless a medical procedure removes the sac entirely.
Understanding Pilar Cysts
Pilar cysts, also known as trichilemmal cysts, originate from the outer root sheath of the hair follicle, which is why over 90% of them are found on the scalp. They occur in approximately 5% to 10% of the population and are the most common type of cutaneous cyst found on the head. These lesions are benign and often present as single or multiple flesh-colored nodules beneath the skin surface.
The cyst is a closed sac structure lined by stratified squamous epithelium, similar to hair follicle tissue. This sac is filled with a dense, cheese-like material consisting primarily of keratin, the protein that makes up hair and nails. This keratinization process gives the cyst its thick, durable wall.
The contents are not sebum or pus, but rather a buildup of protein material continuously shed internally by the cyst wall. The cysts range in size, typically from pea-sized to a few centimeters. Their slow growth rate can make them unnoticeable for years.
The Natural Progression of Pilar Cysts
Because a pilar cyst consists of a complete sac that actively produces and accumulates keratin internally, the body cannot spontaneously reabsorb or eliminate it. The continuous shedding of keratin into the enclosed space prevents the cyst from shrinking or dissolving naturally. This structural characteristic is the fundamental reason why the cyst remains under the skin.
If left untreated, the cyst typically remains stable in size or grows very slowly over months or years. Growth is usually asymptomatic, but a large cyst can cause discomfort, especially if located over a bony area or if it interferes with hair brushing. The cyst may also become inflamed or rupture due to trauma, leading to pain, redness, and swelling.
If infection occurs, the area becomes warm and tender, requiring medical attention. While some sources mention the possibility of a cyst healing on its own, this is rare and usually refers to a temporary reduction in swelling, not the complete disappearance of the sac. The persistent cyst wall causes the lesion to recur or refill if only the contents are expressed.
Medical Intervention Options
Since pilar cysts do not reliably resolve on their own, professional medical removal is the only way to ensure the lump is permanently gone. The standard treatment is surgical excision, a minor, in-office procedure performed under local anesthesia. This technique involves making an incision over the nodule and carefully removing the entire cyst, including the sac wall.
The complete removal of the wall is the most important step because it eliminates the keratin-producing structure, preventing the cyst from refilling and recurring. A minimal excision technique is often preferred, utilizing a small incision (typically only a few millimeters) through which the cyst contents are expressed and the intact sac is pulled out. This minimizes scarring while achieving a permanent result.
Drainage alone, where only the keratin material is removed, is ineffective as a long-term solution because the remaining sac will eventually accumulate contents again. Intervention is recommended if the cyst is infected, growing rapidly, or causing pain, though many patients choose removal for cosmetic reasons. If a cyst is acutely inflamed or infected, a doctor may prescribe antibiotics first to reduce swelling before proceeding with surgical excision.