Neuroendocrine Carcinoma of the Breast – Real versus Mimic

Primary neuroendocrine carcinoma of the breast is a rare entity and is difcult to differentiate from invasive ductal carcinoma with neuroendocrine differentiation especially on small core biopsy specimens. Here we present one such challenging case of a 69 years old female who presented with invasive ductal carcinoma of the breast with neuroendocrine differentiation. The biopsy specimen showed predominately invasive high grade tumor staining for neuroendocrine markers and negative cytokeratin markers, supporting a diagnosis of neuroendocrine carcinoma. Follow up mastectomy showed in situ and invasive ductal carcinoma with neuroendocrine differentiation. This case highlights the challenges of differentiating between these closely similar entities with overlapping features. Clinical history, thorough morphological examination and immunohistochemistry are needed to accurately classify these tumors as the treatment and prognosis vary signicantly