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Abstract

Basal cell carcinoma (BCC) is the most common skin cancer in the U.S., comprising  nearly 80% of non-melanoma skin cancers. Trichoepithelioma (TE) is a benign adnexal tumor that closely mimics BCC both clinically and histologically, often presenting as pink to flesh-colored papules or nodules on sun-exposed areas. Both show basaloid epithelial islands extending into the dermis, leading to diagnostic ambiguity. Definitive diagnosis depends on histopathology, often aided by immunohistochemical stains such as CD10, CD34, and BCL2. However, these stains are not definitive and require expert interpretation, which can further introduce ambiguity. Accurate differentiation is crucial, as treatment ranges from excision to observation. SOX10 and PRAME, commonly used in melanoma diagnosis, have recently shown promise in distinguishing BCC from non-melanocytic tumors. We hypothesized that BCC would demonstrate higher PRAME and SOX10 staining compared to TE. We conducted a retrospective chart review of patients diagnosed with BCC or TE from 2020 to 2025. Biopsied specimens were stained with PRAME or SOX10 and evaluated by a blinded dermatopathologist. Among the cases reviewed, TE tumors (n=7) showed 0% PRAME positivity, while BCC tumors (n=8) demonstrated 63% positivity (p < 0.05). Our findings suggest PRAME may be helpful in excluding TE in diagnostically uncertain cases. Further studies are warranted to determine whether combining PRAME with other stains could improve diagnostic accuracy between BCC and TE.