Cysts are usually small lumps that can form underneath the skin, usually without any noticeable symptoms or harmful effects. Pilar cysts, also known as trichilemmal cysts, originate around the hair follicle and manifest on the skin, especially the scalp. Typically, these cysts are round or dome-shaped and yellow or white in color. Pilar cysts grow slowly, are typically harmless, and may even disappear on their own. However, surgical removal of pilar cysts is often done for cosmetic reasons or if the cysts rupture and become painful. Continue reading to learn more about what causes a pilar cyst and how they are treated.

What is a pilar cyst?

Pilar cysts form when there is a buildup of keratin in the skin pore. This blocks the removal of sebaceous gland secretions. The cyst is filled with keratin material (a protein that helps form hair, nails, and skin's outer layer). The cyst wall is of stratified squamous epithelium or skin cells. These types of bumps are quite common and generally don't cause any symptoms or adverse reactions.

Pilar cysts can also be referred to by numerous other names:

Isthmus-catagen cyst
Trichilemmal cysts
Proliferating Trichilemmal cysts
Wen

There are three types of cysts: epidermoid cyst, meibomian cysts (or chalazion), sebaceous cysts, and pilar cysts. Pilar cysts affect about 10% of the population. They are typically harmless and can even disappear on their own. If you need to have pilar cysts removed, a surgeon can do so. However, pilar cysts can reappear after being removed.

How to identify a pilar cyst?

Cysts are small, round, or dome-shaped bumps that can be identified in three primary types: epidermoid cysts, meibomian cysts, and pilar cysts.

Pilar cysts tend to be harmless and can vary in color from yellow to white. They typically range from 0.5 to 5 centimeters in size and grow slowly, which can make them difficult to detect until they reach a certain size.

Pilar cysts occur around hair follicles on the scalp, and hair typically does not grow on the cyst's lump, making it easier to detect.

In contrast to epidermoid cysts, pilar cysts lack a dark point in their center and have less fragile skin coverings.

Keratin, the protein found in skin and hair cells, makes it simple for a physician to identify a pilar cyst under a microscope. It is common for a person to develop multiple pilar cysts simultaneously.

How do pilar cysts differ from epidermoid cysts?

Pilar cysts and epidermoid cysts are both common dermal cysts. However, epidermoid cysts, also known as sebaceous cysts or epidermal inclusion cyst, are different from pilar cysts.

An epidermoid cyst or sebaceous cyst will develop in the top layer of the skin (epidermis). They are most common in young and middle-aged adults. However, anyone can get them. An epidermoid cyst can appear for seemingly no reason, and there is no known way to prevent them.

Pilar cysts or trichilemmal cysts are most commonly found on the scalp near the hair follicle. Pilar cysts are most common in middle-aged women, though anyone can get them. It is common for someone to develop more than one trichilemmal cyst at once. Trichilemmal cysts can sometimes be hereditary.

Both trichilemmal cysts and sebaceous cysts are formed from skin cells called keratin forming under the skin. Both types of skin cysts are filled with fluid or pus and can form anywhere on the skin. While both are typically harmless, they can become painful or irritating. Doctors will remove trichilemmal cysts or epidermoid cysts with a simple procedure.

How do pilar cysts feel?

When a pilar cyst is touched, it feels firm but may move slightly when pressed. However, excessive force can cause pain or soreness. The cysts can become red and painful, leading to an infection.

The thick skin that covers a pilar cyst makes it less likely to rupture. Cysts on the scalp can become entangled in a brush or comb, causing the skin to break and pus to leak from the ruptured cyst.

What causes a pilar cyst?

Keratin plays a crucial role in maintaining the strength and pliability of skin and hair. Normally, when keratin cells die, they migrate to the skin's surface, where they are washed away or shed. However, if these cells penetrate deeper into the skin, they can multiply and form a pilar cyst.

In these cysts, the keratin appears as a thick, white, or yellowish paste. Pilar cysts have a 50% chance of being inherited as an autosomal dominant trait from an affected parent to an affected child but have no known racial predilection. Additionally, they are more prevalent in women than in men, can affect people of any race or ethnicity, and typically manifest in middle-aged adults.

Although there are no known risk factors for the development of pilar cysts, those with damaged hair follicles or injured skin may be more prone to developing them.

Complications of Pilar cysts

Although pilar cyst complications are uncommon, they can still occur. Such complications may involve:

Tumor

Occasionally, a pilar cyst may transform into proliferating trichilemmal tumors, which is a rare hair follicle tumor. This tumor is typically benign but can become malignant lesions in rare instances. The cells within the cyst reproduce, causing the lump to expand and potentially form an ulcer or multiple lesions. This transformation is rare, and only 3% of pilar cyst incidents develop into trichilemmal tumors.

Infection

When bacteria penetrate the cyst, there is a possibility of an infection. If not treated, the infection can spread from the initial cyst to the surrounding tissue and bone. However, it is important to note that complications arising from a pilar cyst are rare.

Regrowth of skin cyst

After the removal of a pilar cyst, a scar will develop. However, even after surgical removal of the cyst, there is a possibility for it to regrow. It is important to note that in rare cases, the cyst may transform into a proliferating trichilemmal cyst, which causes the cells within the cyst to reproduce and potentially form an ulcer. Nevertheless, these growths are typically benign and grow slowly.

Diagnosing pilar cysts

It's important to have any skin lumps or bumps checked out by a doctor or dermatologist. While cysts are typically not concerning, receiving an accurate diagnosis is crucial.

During your visit, the doctor will perform a thorough examination of the cyst and inquire about any relevant medical history or accompanying symptoms.

In certain instances, a CT or MRI scan may be required to determine whether or not the cyst has affected deeper soft tissue or bone. If the physician is unable to visually determine the nature of the cyst, he or she may need to remove it and examine it under a microscope to ensure that it is not dangerous.

Pilar cyst surgical treatment

Occasionally, skin cysts can resolve on their own. A warm, clean washcloth applied to the affected area can help reduce swelling and promote healing.

In the event of an infected pilar cyst, antibiotics may be prescribed to treat the infection. However, if the cyst is not causing any discomfort or other symptoms, it may not be necessary to remove it, and the individual may choose to forgo treatment.

Surgical removal of a pilar cyst

Pilar cysts are commonly found on the scalp and can be quite painful if caught while brushing or dressing the hair. If a cyst is causing discomfort, it's possible to have it removed. Before the procedure, a local anesthetic will be administered.

There are two ways to remove the cyst:

A pilar cyst on the scalp can be surgically removed by making a small incision in the skin of the ruptured cyst to drain the fluid. This is often best achieved with a surgical punch, also known as a biopsy.
The doctor may also decide it is best to remove the entire cyst from the scalp without making a cut into it.

It is important to consult with a medical professional to determine the best course of action based on individual circumstances.

Typically, the process of removing a Pilar cyst on the scalp is swift, and one does not need to spend the night in the hospital or clinic. After removal, the physician will apply a dressing to the affected area. It is recommended to avoid getting the dressing wet and to be cautious when touching the injured area.

Conclusion

Pilar cysts are typically found on the scalp near hair follicles. They are harmless and not contagious, but they can become irritated and painful, leading to an infection. In such cases, a doctor may prescribe medication. In rare instances, you may have a tumor form, though it is generally not cancerous. It is possible to have multiple pilar cysts at once, and they may disappear and reappear.

In the majority of cases, cysts do not cause any symptoms and heal without treatment. If necessary, a physician can remove a cyst through a simple surgical treatment. It is important to note that the cyst may return or that new cysts may develop in the future.

References