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Cystic epithelioma: causes, symptoms, diagnosis, treatment
Medical expert of the article
Last reviewed: 07.07.2025
Cystic epithelioma (syn.: proliferating trichilemmal cyst, pilar tumor) is a rather rare tumor, mainly occurring in people over 40 years of age, although the age range is quite wide - from 26 to 87 years. In women, the tumor occurs twice as often as in men. It is localized mainly on the scalp, less often on the face and trunk, the elements are usually solitary. In the early stages, this is a fairly clearly delineated intradermal nodule, displaceable, of a dense-elastic consistency, beginning to protrude above the level of the surrounding skin as it grows. Long-existing formations can reach large sizes - 10 cm or more, forming exophytic nodes on a wide base of a bizarre configuration due to uneven tumor growth. The referral clinical diagnosis is usually limited to some type of cyst - sebaceous, hair, epidermal.
Pathomorphology of cystic epithelioma. The basis of the neoplasm is a cyst of varying size, located in the dermis, sometimes closely associated with the epithelium of the expanded and elongated follicular funnel. Layers of proliferating keratinocytes of varying size and configuration may extend from the epithelial lining of the cyst, forming solid and cyst-like structures. The complexes consist of basal and spinous layers containing keratinocytes with abundant pinkish cytoplasm, unclear intercellular bridges. Granular cells are absent. Sometimes, solid complexes exhibit processes of dyskeratosis, nuclear atypia, and mitotic activity. Cyst-like structures have a wall resembling the epithelial lining of the follicle in the isthmus zone, and in the central part are filled with compact (homogeneous) keratin. When damaged, granulomatous inflammation, the appearance of erythrocyte extravasates, and multiple siderophages may occur.
The greatest difficulties in differential diagnosis with squamous cell carcinoma may be caused by areas of cystic epithelioma with dyskeratosis, atypia and mitotic activity. In squamous cell carcinoma, these phenomena are expressed to a much greater extent, in addition, an assessment of the tumor configuration at low magnification may help in differential diagnosis - clear smooth borders of the element are more characteristic of cystic epithelioma.
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