What is a Pilar Cyst?
A pilar cyst, also known as a trichilemmal cyst, is most often located on the scalp and occurs in 5-10% of the population. Women tend to be affected slightly more than men, and there is a strong genetic correlation. It originates from the outer hair root sheath and is filled with keratin, the protein that makes up hair and nails. Unlike Epidermal Inclusion Cysts (EIC) that are filled with sebaceous material and are commonly located on the face or body, these cysts do not have a central opening and are less likely to become inflamed. Although they are benign, they can become quite large and bothersome and rarely resolve without treatment. Therefore, many patients prefer to have them removed.
What Do Pilar Cysts Look Like?
A pilar cyst may be small at first, appearing rounded or dome-shaped. Most of these cysts grow at a slow pace and may not be noticed until a certain size is reached. A new pilar cyst may measure as little as .5 centimeters and may eventually grow to the size of a quarter or small ball. The cyst may develop a white or yellow hue at some point.Hair usually does not grow on the pilar cyst, so a larger cyst may cause the appearance of thinning hair or a bald spot.
Cysts are fluid-filled, so a pilar cyst may move slightly when touched but usually feels somewhat firm. It is important not to press hard on the cyst, as this will cause unnecessary pain. The pilar cyst should not be squeezed or popped. Because the skin that lies over the cyst tends to thicken, there is minimal chance that tissue would break open. However, catching the cyst with a brush or styling tool could lead to oozing and discomfort. A nick to the cyst could also lead to infection, so the cyst needs to be monitored for signs of inflammation such as redness and tenderness.
Where On The Body Are Pilar Cysts Found?
Are Pilar Cysts Common?
What Causes A Pilar Cyst?
Diagnosing Pilar Cysts
It may be possible to observe a pilar cyst based on appearance alone. However, it is beneficial to have any growth or cyst examined by a dermatologist for the most accurate diagnosis. A dermatologic exam visualizes the skin overlying the cyst and palpates the cyst for texture and firmness. A biopsy may be taken to obtain a small sample of tissue for microscopic examination. In some cases, a CT scan may be ordered. This non-invasive imaging test can capture the internal aspects of the cyst and potentially observe if more cysts are forming in the immediate area of the first.
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