Invasive neuroendocrine carcinoma of the breast: A rare variant of invasive breast carcinoma with prognostic and therapeutic implications - a small case series

Abstract

Primary neuroendocrine (NE) breast tumours were recognised as a separate entity in the WHO classification of breast tumours in 2003. They are a rare entity when applying the WHO rule of at least 50% NE differentiation required to be classified under this diagnostic group. NE breast tumours are not well recognised or studied. Previous case series and reports are limited in number and give conflicting results. We report a small case series of three patients with invasive NE breast cancer and one case of small cell breast cancer. The diagnosis was suspected on the morphological appearances and the immunohistochemistry confirmed the neuroendocrine differentiation with 100% positivity to synaptophysin in two cases and patchy but significant positivity in the other two. We report the cases and discuss recent studies that suggest diagnosing NE breast cancer has therapeutic and prognostic implications. Providing this extra piece of information could be useful to the surgeons and oncologists caring for breast cancer patients.