Bilateral primary breast neuroendocrine carcinoma in a young woman: report of a case.

Bilateral breast carcinoma accounts for approximately 5% of all patients with breast cancer, while neuroendocrine breast carcinomas comprise less than 5% of invasive breast carcinomas. In addition, most patients with breast neuroendocrine carcinomas are older. Therefore, bilateral primary breast neuroendocrine carcinoma at a young age is extremely rare. We herein report bilateral neuroendocrine carcinoma of the breast in a 29-year-old woman who underwent bilateral lumpectomy with the initial symptom of bilateral nipple discharge. Grossly, the lesions in both breasts were masses with infinite margins. Histologically, this case was consistent with primary neuroendocrine carcinoma arising in bilateral breasts. Cells from both breast tumors were positive for chromogranin A, neuron-specific enolase, synaptophysin, cytokeratin 7, estrogen receptor, and progesterone receptor, and negative for Her2, cytokeratin 34β12, cytokeratin 5/6, smooth muscle actin, p63, S-100 protein, and p53. The Ki67 and NE proliferative indices were below 1%. To the best of our knowledge, this is the first reported case in China of bilateral primary neuroendocrine carcinoma presenting in a young woman.