Abstract
BACKGROUND: High grade basal-like breast carcinomas are triple negative, express basal cytokeratins, and are known for the overall poor prognosis and aggressive behavior. HPV related multiphenotypic sino-nasal carcinoma has overlapping histology with basal-like breast carcinomas, but carry the defining feature of association with high risk HPV. CASE PRESENTATION: We present a case of a perimenopausal woman with a non-healing ulcerated lesion involving the nipple and breast following a trauma. Biopsy performed showed an HPV-positive basal-like carcinoma with squamous differentiation involving the breast, analogous to multiphenotypic carcinoma previously described in the sinonasal tract. CONCLUSION: This is the first report of a case of a high- risk HPV related basal-like carcinoma with squamous differentiation, described in the literature. We highlight the morphology and immunophenotype of this lesion and its recognition when compared to other multiphenotypic lesions of the breast, and suggest that pathologists should consider HPV evaluation when encountering similar basal-like tumors involving the breast.