FINE-NEEDLE ASPIRATION CYTOLOGY OF MALE BREAST-CARCINOMA EXHIBITING NEUROENDOCRINE DIFFERENTIATION - REPORT OF A CASE WITH IMMUNOHISTOCHEMICAL, FLOW CYTOMETRIC AND ULTRASOUND ANALYSIS

We present the cytologic, immunohistochemical, flow cytometric and ult rastructural findings of a case of invasive ductal carcinoma of the br east with features of neuroendocrine differentiation occurring in an 8 3-year-old male. Fine needle aspiration (FNA) cytology of the patient' s tumor demonstrated a markedly cellular specimen of discohesive tumor cells, present primarily singly, with occasional loose groups. The ce lls were relatively large, with pleomorphic, eccentrically placed, rou nd to oval nuclei. The cytoplasm was abundant and contained prominent red granules (Papanicolaou stain) that were also argyrophilic. Immunoh istochemical studies performed on the aspirate and the subsequently ex cised malignant breast tissue revealed positive staining for neuron-sp ecific enolase, chromogranin A, synaptophysin and gastrin. Also, the m ajority of the tumor stained positive with antibodies to both estrogen and progesterone hormone receptors. DNA flow cytometry demonstrated a n aneuploid stemline population with a DNA index of 1.73 and an S-phas e fraction of 4.5%. Electron microscopy was performed on the FNA mater ial, and numerous variable-sized, membrane-bound, dense-core granules diffusely scattered within the cytoplasm of the neoplastic cells were identified. The specific cytologic features of this tumor, along with the immunocytochemical and ultrastructural features, can aid the patho logist in rendering an accurate FNA diagnosis of this specific subtype of breast carcinoma.