Basaloid squamous cell carcinoma of the breast

Basaloid squamous cell carcinoma (BSCC) is a subtype of squamous cell carcinoma that characteristically occurs in the head and neck, may be related to HPV infection and is usually considered to be aggressive. We present the first description of BSCC of the breast. The tumor exhibited characteristic histologic features of BSCC, including nests of basaloid squamous cells with comedonecrosis, abrupt keratinization, and abundant hyaline basement membrane-like material deposition. The tumor showed immunohistochemical features of triple negativity, diffuse p63 positivity, p16 positivity, and Rb negativity. HPV immunogenotyping was negative. The patient was free of disease after treatment with breast conserving surgery, chemotherapy and radiotherapy. BSCC of the breast should be distinguished from basaloid adenoid cystic carcinoma, triple-negative basal-like breast cancer and nonbasaloid squamous cell carcinoma of the breast based on histology and immunohistochemistry. The prognostic implications of BSCC of the breast should be further studied in larger series.