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Hair cyst: causes, symptoms, diagnosis, treatment
Last reviewed: 07.07.2025
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A pilar cyst [syn.: trichilemmal (pilar) cyst, follicular cyst, sebaceous cyst] can be single or multiple, especially in women over 40. It occurs mainly on the scalp, less often on the skin of the back and other places, can exist from birth or, more often, appears in old age, reaches a significant size, has a dense elastic consistency, and is painless. Familial forms often occur, inherited, probably in an autosomal dominant manner.
Pathomorphology of the hair cyst. The wall of the hair cyst is lined with epithelium similar in structure to the epithelium in the area of the isthmus of the hair follicle, which is characterized by the presence of basal and spinous layers and the absence of granular. The contents of the cyst consist of homogeneous keratin, sometimes with deposits of cholesterol and fatty acid crystals. In 25% of cases, calcification of the cyst occurs. When the cyst wall ruptures, a giant cell reaction may be observed around its contents.
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