A rare adnexal tumor: desmoplastic trichilemmoma

Abstract

Background: Desmoplastic trichilemmoma (DT) is a rare benign cutaneous adnexal tumor originating from the outer root sheath of hair follicles. Histologically, it is characterized by a prominent desmoplastic stroma that may resemble invasive malignancies, particularly basal cell carcinoma, making accurate diagnosis is essential to avoid overtreatment. DT most frequently arises in sun-exposed areas of elderly population and is rarely found on the eyelid.

Case Illustration: We report a case of a 66-year-old male with a 1 cm, skin-colored, dome-shaped nodule on the left upper eyelid, present for four years. Histopathological examination revealed a well-circumscribed dermal tumor composed of clear cells arranged in nests and cords with peripheral palisading, embedded in dense, hyalinized stroma. No atypia or mitotic activity was noted. The diagnosis of DT was confirmed.

Discussion: DT is a variant of trichilemmoma with unique histologic features that can resemble infiltrative neoplasms. Eyelid involvement is particularly challenging due to cosmetic and functional considerations. Immunohistochemistry may assist in distinguishing DT from basal cell carcinoma, with CD34 positivity and BerEP4 negativity supporting the diagnosis.

Conclusions: In conclusion, DT should be included in the differential diagnosis of benign-appearing eyelid lesions that demonstrate histologic features suggestive of malignancy. Proper identification is crucial to ensure appropriate surgical management and to prevent unnecessary aggressive treatment.