Locally Advanced Primary Small Cell Carcinoma of the Breast: A Case Report and Review of Current Evidence

Small-cell breast carcinoma (SCBC) is a very rare type of aggressive breast cancer constituting less than 1% of all breast cancers. The WHO classification categorizes this tumor as small-cell neuroendocrine carcinoma, and its prognosis is usually worse as compared to invasive breast cancers. We report a 64-year-old Caucasian female who presented with a large fungating left breast mass. Biopsy of the mass revealed small-cell carcinoma of the breast, negative for all 3 receptors (estrogen, progesterone, and Her2/neu). Imaging studies were negative for distant metastasis. She was subsequently treated after multidisciplinary discussion utilizing neoadjuvant chemotherapy with platinum agents and etoposide, modified radical mastectomy with axillary lymph node dissection, and adjuvant radiation therapy. Since she has triple-negative small-cell breast cancer, she will be followed with active surveillance without hormonal therapy. With less than 100 cases reported and in the absence of evidence-based standard treatment guidelines, we have reviewed various case series reported in the literature. We further discuss various chemotherapy regimens used previously, adverse prognostic factors of breast neuroendocrine tumors, common receptor status, and genetic mutations found in SCBC.