Primary neuroendocrine breast carcinoma, well differentiated

Primary neuroendocrine tumor of breast is a rare tumor, with few cases reported each year and with an incidence less than 1% from all neuroendocrine tumors. In our report we present a case of a postmenopausal woman with a lump in her left breast whose histopathological aspect was strongly suggestive for primary solid neuroendocrine breast carcinoma. Immunohistochemical examination has been done using a panel of seven biomarkers in order to confirm our initial diagnose and both prognostic and predictive factors. We used cromogranin A, synaptophysin and neuron-specific enolase as neuroendocrine biomarkers. Diagnose was proved by a positive reaction in more than 50% of tumor cells for the first two antibodies. Immunophenotype of the tumor (estrogen and progesterone receptor positive, low Ki6 index and no supraexpression of HER2) is consisted with luminal A molecular subtype. The prognosis was good based on clinic-pathological features and immunohistochemical expression. The patient has a good clinical evolution after surgical treatment and adjuvant therapy, with no local recurrence or distant metastasis after 3 years of surveillance.