Argyrophilic neuroendocrine carcinoma of the male breast.

A case of breast carcinoma with neuroendocrine features occurring in an elderly male patient is reported. Histologically, the tumor was characterized by solid growth with nests and ribbons of small to medium-size uniform neoplastic cells. Argyrophilia, expression of chromogranins at both protein and gene level, and the presence of dense granules of the neurosecretory type by electron microscopy were demonstrated.