The case of a 67-year-old woman with a solid breast neuroendocrine carcinoma is presented. Cytological findings for breast neuroendocrine carcinoma have rarely been described. Cytopathologic examination using a fine needle aspiration (FNA) sample of the tumor revealed clusters of relatively uniform tumor cells. The tumor cells had round to oval nuclei with little to mild atypia, fine granular chromatin, and showed rosette formation. These features strongly suggested a neuroendocrine tumor, which was confirmed by a histopathologic examination of the resected specimen. The diagnosis of neuroendocrine carcinoma was further confirmed by immunostaining for neuron-specific enolase/chromogranin A/synaptophysin. Preoperative FNA successfully predicted this special type of breast carcinoma.
