The differential IHC staining among trichoblastomas/trichoepitheliomas and basal cell carcinomas, including highlighting perifollicular mesenchymal cells and papillary mesenchymal bodies in TB and TE, combined with the staining pattern in normal hair follicles, suggests that TRPS1 may be used as a marker of hair follicle differentiation. The gene discussed is TRPS1; the disease is trichoblastoma.