Primary neuroendocrine carcinoma of the breast with markedly elevated alpha-fetoprotein: a case report

Primary neuroendocrine carcinoma of the breast (PNECB) is a relatively rare subtype of breast cancer that has seldom been studied since its initial description. At present, the pathogenesis of the disease remains unknown, and there exit no specific clinical guidelines or specifications for its diagnosis and treatment. In addition, alpha-fetoprotein (AFP)-despite being a tumor marker-plays a small role in the diagnosis of breast cancer. Here, we explain the diagnosis and treatment of primary neuroendocrine (NE) breast carcinoma in a patient with a markedly elevated level of AFP. A 52-year-old woman visited our hospital, reporting she had palpated a nodule in her left breast 1 day before admission. After ultrasonographic detection of the hypoechoic lesion in her left breast-which was classified according to the Breast Imaging Reporting and Data System (BI-RADS) as grade 4C-and the abnormal enlargement of her left axillary lymph nodes, the patient was referred to our department as a case of malignant breast tumor. Meanwhile, the level of the tumor marker AFP was found to be over 1,210 ng/mL (0-7 ng/mL). And the patient had no past medical history of increased AFP, abnormal liver function, or gastrointestinal tumor. Analysis of the surgical specimens obtained from the left breast showed grade II invasive ductal carcinoma with NE differentiation. After discussion with a multidisciplinary team (MDT), according to the results of pathological and immunohistochemical examinations, the patient was diagnosed with PNECB. Due to axillary lymph node metastasis, she received combined chemotherapy with cyclophosphamide, epirubicin, and paclitaxel on postoperative day 13. Up to now, six cycles of chemotherapy have been successfully administered, with no evidence of adverse reactions. AFP levels were all above 1,210 ng/mL during chemotherapy. At the time of submission, the patient has been followed up for 10 months and there has been axillary lymph node metastasis, but no tumors in other parts have been found. Therefore, we think that the increase in AFP levels is related to the occurrence and poor prognosis of PNECB.