Desmoplastic Trichilemmoma Mimicking Basal Cell Carcinoma: Two New Cases, Systematic Review of 92 Cases and Dual Staining Diagnostic Approach.

Abstract

Abstract: Desmoplastic trichilemmoma (DTM) is a rare and benign variant of conventional trichilemmoma which presents a diagnostic challenge. It closely mimics malignant neoplasms, particularly basal cell carcinoma (BCC), because of overlapping clinical and histopathological features. Accurate differentiation is crucial to prevent misdiagnosis and management. The aim of this study was to synthesize the available clinical and histopathological data on DTM by presenting 2 new cases and conducting a systematic review of the literature. A retrospective query was conducted of database from 2012 to 2026 identifying 2 DTM cases. In addition, a systematic review of the PubMed database was performed for English language publications from 1990 to present day, yielding 29 publications for inclusion. The addition of 2 new cases brings the total number of DTMs in the compiled dataset to 94 cases. DTM typically presents as a solitary lesion on the head and neck of older adults, ranging in size from 0.3 to 7 cm, with rare cases reported on the chest, vulva, and lower extremities. Histopathologically, its lobular and cord-like growth pattern, peripheral palisading, and desmoplastic stroma closely mimic BCC. Immunohistochemically, the current cases showed immunoreactivity for CD34 and a concurrent negativity for BerEP4. Based on the current findings and review data, 8 CD34-positive/BerEP4-negative and 10 CD34-positive DTMs were identified. Accurate distinction between DTM and BCC requires careful histological examination, which is enhanced by the application of the proposed CD34-BerEP4 dual-marker approach. This diagnostic utility guides appropriate clinical management and prevents unnecessary or inadequate treatment.