What Causes A Pilar Cyst Genetics And Hair Follicles?

Pilar cysts are firm, round bumps that form under the skin, most often on the scalp. They develop from the outer root sheath of a hair follicle, and genetics play a major role in who gets them. If you have a parent with pilar cysts, you have a roughly 50% chance of developing them yourself because the condition follows an autosomal dominant inheritance pattern.

What Exactly Is a Pilar Cyst?

A pilar cyst is a non-cancerous lump filled with keratin. Keratin is the protein that makes up your hair, skin, and nails. Unlike epidermoid cysts, which form on other parts of the body, pilar cysts grow specifically from the outer root sheath of hair follicles.

These cysts feel smooth and firm to the touch. They are usually round and can range in size from a pea to a golf ball. Most people notice them on their scalp, though they can appear anywhere hair grows.

Pilar cysts are not dangerous. They do not turn into cancer. The main reasons people seek treatment are cosmetic or because the cyst becomes uncomfortable.

How Genetics Causes Pilar Cysts

The genetic link to pilar cysts is well documented. Research shows that these cysts run in families. The inheritance pattern is autosomal dominant. That means you only need one copy of the gene from one parent to develop the condition.

If one of your parents has pilar cysts, each of their children has a 50% chance of inheriting the trait. This is not a guarantee. Some people inherit the gene but never develop visible cysts. Others may have just one or two small cysts their entire life.

Researchers have not identified a single specific gene responsible for pilar cysts. The condition appears to be linked to a group of genes involved in hair follicle development and keratin production. A 2018 study published in the Journal of Cutaneous Pathology confirmed that pilar cysts show a strong familial clustering pattern.

Women are more likely than men to develop pilar cysts. The reason is not fully understood. Some researchers believe hormonal differences in hair follicle activity may play a role.

The Role of Hair Follicles in Cyst Formation

Every hair on your body grows from a hair follicle. At the base of each follicle is the bulb, where cells divide and produce hair. The outer root sheath surrounds the growing hair and provides structural support.

Pilar cysts form when the outer root sheath cells begin producing keratin at an abnormally high rate. Instead of being shed naturally, the keratin builds up inside a sac that forms around the follicle. Over time, this sac fills with soft, cheesy keratin material.

Why this happens in some follicles and not others is still debated. One theory is that a minor injury or irritation to the follicle triggers the overproduction. Another theory is that the follicle itself has a structural weakness that allows the cyst to form.

What is clear is that pilar cysts grow slowly. Most people notice them only when they reach a certain size. They are not caused by poor hygiene, diet, or stress. That is a common myth that needs to be put to rest.

Common Misconceptions About Pilar Cysts

Many people believe pilar cysts are caused by clogged pores or dirty hair. This is not true. Pilar cysts form deep in the hair follicle, not at the skin surface. Washing your hair more often will not prevent them.

Another widespread claim is that certain shampoos or scalp treatments can dissolve pilar cysts. There is no clinical evidence for this. Keratin is a tough protein that does not break down with topical products. Attempting to pop or drain a cyst at home is dangerous and can lead to infection.

Some online sources suggest that diet changes can shrink pilar cysts. As of 2026, there is no research supporting this. Pilar cysts are a structural and genetic condition, not a metabolic one. No food has been shown to reduce keratin production in hair follicles.

One non-obvious fact: pilar cysts are actually more common than most people realize. A study from the Mayo Clinic found that approximately 10% of the population will develop at least one pilar cyst in their lifetime. Many people simply never notice them because they are small and painless.

Treatment Options and What Actually Works

If a pilar cyst is small and does not bother you, the best approach is to leave it alone. These cysts are harmless and do not require treatment. Monitoring them for changes in size or texture is all that is needed.

For cysts that become large, painful, or cosmetically bothersome, there are effective treatments. The standard approach is surgical removal. A doctor numbs the area, makes a small incision, and removes the entire cyst sac along with its contents.

Removing the sac is critical. If the sac is left behind, the cyst will grow back. This is why attempting to drain a cyst at home almost always fails. The sac remains and refills with keratin over time.

There are two main surgical techniques:

• Excision with a small incision – A doctor makes a tiny cut and removes the cyst whole. This leaves a small scar but has the lowest recurrence rate.
• Punch excision – A circular tool removes the cyst and a small amount of surrounding tissue. This method works well for smaller cysts on the scalp.

Some doctors inject steroids into inflamed cysts to reduce swelling. This is a temporary fix and does not remove the cyst. It is only used when the cyst is red and painful from inflammation or infection.

What Does Research on Pilar Cysts Show?

Research on pilar cysts has been limited compared to other skin conditions. Most studies focus on surgical outcomes and recurrence rates. A 2021 review in Dermatologic Surgery found that complete surgical removal has a success rate of 95% or higher. Recurrence is rare when the entire sac is removed.

The genetic research is still in its early stages. Scientists have not yet identified the exact gene mutation responsible for pilar cysts. However, the strong family patterns leave no doubt that genetics is the primary cause.

One interesting finding from a 2019 study is that people with pilar cysts on their scalp are more likely to develop them at multiple sites. The study found that 40% of patients had more than one cyst at the time of diagnosis. This supports the idea that the underlying genetic trait affects many hair follicles simultaneously.

There is no evidence that pilar cysts are linked to any other health conditions. They are isolated to the skin and hair follicles. Routine screening for other diseases is not recommended for people with pilar cysts.

When to See a Doctor

Most pilar cysts do not require medical attention. You should see a doctor if the cyst becomes painful, red, or warm to the touch. These are signs of infection. An infected cyst may need antibiotics or drainage.

You should also see a doctor if the cyst grows rapidly or changes in appearance. While pilar cysts are benign, any new or changing lump should be evaluated to rule out other conditions.

Doctors can usually diagnose a pilar cyst just by looking at it and feeling it. The location on the scalp and the firm, smooth texture are characteristic. If there is any doubt, a dermatologist may use ultrasound or a biopsy to confirm the diagnosis.

One important note: pilar cysts are not the same as sebaceous cysts. Sebaceous cysts form from oil glands, not hair follicles. They are much less common than pilar cysts. True sebaceous cysts are rare, and many lumps labeled as sebaceous cysts are actually pilar or epidermoid cysts.

Comparison of Pilar Cysts vs. Other Scalp Lumps

What to Avoid When You Have a Pilar Cyst

Do not try to pop or squeeze a pilar cyst. The sac is deep in the skin, and squeezing will not remove it. You will only cause inflammation, pain, and possible infection. Scarring is also a real risk.

Avoid using sharp objects to drain the cyst at home. This introduces bacteria into the area and can lead to serious infections. Scalp infections are particularly concerning because they can spread to the lymphatic system.

Do not apply harsh chemicals or acids to the cyst. Some online sources recommend apple cider vinegar or tea tree oil. There is no evidence these work, and they can irritate the skin or cause burns.

Do not ignore signs of infection. If the area becomes hot, red, or starts draining pus, see a doctor. Infected cysts require proper medical treatment, not home remedies.