Pigmented trichoblastoma developed in a sebaceous nevus: HRAS mutation as a common molecular driver

Deborah Saraggi1, 3, Roberto Salmaso1, Elisa Valentini1, Giada Munari1, Vincenzo Vindigni2, Massimo Rugge1, Matteo Fassan1, Lorenzo Cerroni3
1 Department of Medicine (DIMED), Surgical Pathology Unit, University of Padua, Padua, Italy
2 Clinic of Plastic and Reconstructive Surgery, University of Padua, Padua, Italy
3 Research Unit Dermatopathology, Department of Dermatology, Medical University of Graz, Graz, Austria
A 40-year-old woman presented with a pigmented nodule on a previously existing yellowish, verrucous plaque on the scalp. The histological diagnosis was consistent with a pigmented trichoblastoma developed within a sebaceous nevus (SN). A multigene hotspot mutational profiling of the BRAF, NRAS, HRAS and KRAS genes was carried out, and a shared G13R HRAS mutation in both the trichoblastoma and the sebaceous nevus components was found. These data support a common molecular landscape of the two lesions.
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