Fine needle aspiration cytology of solid neuroendocrine carcinoma of the breast: a case report.

We report a case of neuroendcrine (NE) carcinoma in the right breast of a 67-year-old female, ultrasonography revealed a lesion composed of irregular hypoechoic masses and mammography showed asymmetric breast tissue. Histopathologic examination of the surgical sample showed a solid to nested proliferation of plasmacytoid cells that showed immunocytochemical positivity for chromogranin A, synaptophysin, CD56, and estrogen receptor. Our case was diagnosed as solid NE carcinoma. Though the findings of fine needle aspiration cytology reflected the histological features, we were not able to cytopathologic grounds only to predict the NE nature of this tumor. We performed immunocytochemistry using Chromogranin A, Synaptophysin, and CD56 on our cytologic smear retrospectively with positive results for all of the markers. When the cytopathologic examination of a given breast neoplasm is suggestive of NE differentiation, immunocytochemical staining for NE markers is generally useful for a correct preoperative diagnosis. An acurate preoperative diagnosis of NE carcinoma on FNAC can be achieved based on its distinctive cytomorphologic and immunocytochemical features.