Desmoplastic Trichoepithelioma

Desmoplastic trichoepithelioma (DTE) is an uncommon benign adnexal tumor originating from the hair follicle, first described by Zeligman in 1960 as a "solitary trichoepithelioma." The lesion is classified into 3 subgroups: multiple familial trichoepithelioma, solitary nonhereditary trichoepithelioma, and desmoplastic trichoepithelioma. In 1977, MacDonald et al referred to DTE as a "sclerosing epithelial hamartoma," and Brownstein and Shapiro later coined the term "desmoplastic trichoepithelioma," which remains in use today.

Typically presenting as an asymptomatic annular, papular nodule with a "thread-like elevated border," DTE is usually <2 cm in diameter and commonly occurs in young to middle-aged women, particularly in cosmetically sensitive areas such as the cheeks, forehead, and chin. Histopathologically, DTE is characterized by nests and cords of basaloid cells within a dense, fibrous stroma, occasionally containing small cystic spaces filled with keratinous material. Peripheral palisading of cells is observed; significant mitotic activity is generally absent. These features distinguish DTE from other skin neoplasms like basal cell carcinoma (BCC) and microcystic adnexal carcinoma, which exhibit more aggressive histologic features.

Clinically, DTE manifests as a slow-growing, skin-colored facial plaque or nodule with a depressed center, developing very slowly before stabilizing. Despite its benign nature and low risk of malignant transformation, DTE tends to grow if untreated and has a propensity for recurrence due to its poorly circumscribed histologic growth pattern. Familial cases have been reported, suggesting a potential genetic predisposition. Often an incidental finding during routine skin cancer examinations, DTE can frequently be diagnosed clinically by experienced dermatologists. The preferred treatment is surgical excision, with Mohs micrographic surgery recommended to ensure clear margins, especially in cosmetically challenging areas like the face.

DTE is a unique tumor due to its benign nature, distinct histopathological features, and superficial invasion. Accurate diagnosis relies on careful clinical and histopathological evaluation to distinguish it from more aggressive neoplasms.