Squamous cell carcinoma with apocrine features of the breast: A case report

A rare case of squamous cell carcinoma (SCC) with apocrine features was investigated; the focus was on the histological characteristics of the cancer cells in a 68-year-old female exhibiting an ulcerated lesion of the right breast. Diagnostic imaging methods identified a lobulated solid tumor and indicated multiple enlarged lymph nodes in the left axilla, which confirmed the diagnosis of advanced breast cancer; thus, a mastectomy was performed. Macroscopic investigations identified the tumor as a white, solid lesion measuring 66 × 68 × 47 mm, which exhibited necrosis. Histologically, the tumor was predominantly solid and exhibited nest patterns, in addition to intracellular keratinization. Immunohistochemical staining identified the tumor cells as positive for cytokeratin 5/6, 34βE12 and P63. The lesion was considered to be an SCC demonstrating negative expression for the human epidermal growth factor receptor 2, estrogen receptor and progesterone receptor; therefore, the tumor was a triple-negative breast cancer. Conversely, approximately one-third of the tumor cells indicated abundant eosinophilic cytoplasm and gross cystic disease fluid, which was demonstrated via protein-15 staining; this indicated the presence of apocrine features. In addition, the androgen receptor was expressed in the tumor cells, thus the lesion was diagnosed as an SCC of the breast, exhibiting apocrine features.