Primary large cell neuroendocrine carcinoma of the breast, a case report with an unusual clinical course.

Large cell neuroendocrine carcinoma of the breast (NECB) is an extremely rare type of breast cancer; little is known about effective chemotherapies, and data on pathologic response to treatment are unavailable. We report the case of a 34-years-old woman with large cell NECB with initial clinical and pathologic evidence of treatment response to anthracycline-containing neo-adjuvant therapy. Histologic reassessment early during anthracycline chemotherapy revealed cell death with necrosis of 50% of the tumor cells seen in the biopsy specimen. After completing neo-adjuvant chemotherapy, the patient underwent breast-conserving surgery. Pathologic evaluation of the surgical specimen showed a partial response but margins were positive for residual carcinoma. Despite repeated neo-adjuvant chemotherapy, radiotherapy, and surgical resection, the tumor grew rapidly between surgeries and recurred systemically. Therefore, we review the literature on large cell NECB and its treatment options.