RESUMEN
Breast cancer is the most common type of cancer of the female gender. A rare subtype of breast cancer is the invasive breast carcinoma (IBC) with neuroendocrine (NE) differentiation. Its incident is believed to be 0.1% to 5% of all breast cancers. We report a rare case of a 66-year old woman who presented with an isolated nodule of the left breast. The patient underwent modified radical mastectomy. Pathology revealed invasive breast carcinoma with neuroendocrine differentiation. Invasive breast carcinoma is an extremely rare group of neoplasms, the exact frequency of which cannot be determined with current data. Therefore, it is necessary for future studies to focus on the pathophysiology of this subtype of breast cancer and on the potential therapeutic approaches.