Pilar cysts are common, benign skin growths that often appear on the scalp. This article explores what pilar cysts are, their connection to hair follicles, and the influence of genetics and family history in their development.
What Exactly is a Pilar Cyst?
A pilar cyst, also known as a trichilemmal cyst or wen, is a non-cancerous growth that forms under the skin. These cysts typically present as smooth, flesh-colored, and mobile lumps. While they can appear anywhere on the body where hair follicles are present, over 90% of pilar cysts are found on the scalp.
Pilar cysts are distinct from other common skin cysts, such as epidermoid cysts, due to their origin. Unlike epidermoid cysts that arise from the surface layer of the skin, pilar cysts originate from the outer root sheath of a hair follicle. They are filled with keratin, a protein found in hair, skin, and nails, often resembling a thick, cheese-like substance.
The Hair Follicle Connection
Pilar cysts directly link to hair follicles, specifically forming from the outer root sheath, a component of the hair follicle. This involves a spontaneous process where cells from this sheath begin to proliferate abnormally. Instead of shedding, these cells become trapped beneath the skin’s surface.
As these cells multiply, they form a sac-like structure. Inside this sac, keratin, a protein, accumulates. This buildup of keratin and old skin cells creates the cyst’s contents, which gradually expands, forming the noticeable lump. This process is an internal cellular event, not triggered by external factors.
The Role of Genetics and Family History
Genetics play a significant part in pilar cyst development, often showing a familial tendency. These cysts can be inherited through an autosomal dominant pattern. This means if one parent carries the genetic predisposition, each child has approximately a 50% chance of inheriting this trait.
While a genetic predisposition increases the likelihood, not every individual who inherits the trait will form these cysts. Research indicates that specific genetic mutations, such as variants in the PLCD1 gene, are associated with their formation in families.
When to Seek Medical Advice for a Pilar Cyst
Although pilar cysts are generally benign and often do not cause discomfort, medical consultation is recommended in specific circumstances. Rapid growth, pain, or tenderness warrant professional evaluation. Signs of inflammation or infection, such as redness, warmth, or pus, also require medical attention.
A ruptured cyst, which can lead to irritation or infection, also requires assessment. If a pilar cyst interferes with daily activities, such as combing hair, or causes cosmetic concern, consulting a doctor can provide reassurance and discuss removal options. Medical evaluation helps rule out other conditions and ensures appropriate management.