Epidermal cyst: causes, symptoms, diagnosis, treatment

An epidermal cyst (syn. infundibular cyst) is a developmental defect. It is a slowly growing, dermo-hypodermal nodular formation localized on the scalp, face, neck and trunk. It can be of various sizes, but usually its diameter does not exceed 5 cm, has round or oval outlines. Multiple cysts are observed in Gardner's syndrome, combined with fibromas, desmoid tumors, osteomas of the skull bones and polyposis of the rectum prone to malignancy.

Pathomorphology. The wall of an epidermal cyst is similar in structure to the epidermis, the contents are lamellar keratin and cholesterol crystals. The wall of long-existing cysts is atrophic, lined with only 2-3 layers of epithelial cells. When the wall is damaged, a granulomatous reaction occurs with the formation of giant cells of foreign bodies, as a result of which the cyst is completely destroyed and resorbed. In some cases, the inflammatory reaction can cause pseudo-epitheliomatous hyperplasia of the remaining areas of the epidermis.

Histogenesis. According to some authors, epidermal cysts are histogenetically associated with the epithelium of the infundibular part of the hair follicle, as well as the intraepidermal sections of the ducts of the eccrine glands. Electron microscopy has shown that the epithelial cells that make up the cyst wall contain aggregated tonofilaments and keratohyalin granules, as in normal epidermis. In places of keratinization of epithelial cells, loss of desmosomes is observed.