Amphicrine carcinoma of the right colon, a report of a case and review of literature

Mixed neuroendocrine and non-neuroendocrine neoplasms, recently recognized in the WHO classification as (MiNEN), are rare tumors of the gastrointestinal tract. These tumors are composed of two distinct cellular components; a well- or poorly differentiated neuroendocrine tumor and a non-neuroendocrine tumor, usually in the form of an adenocarcinoma, either admixed with or adjacent to one another. A rarer phenotype is a tumor in which the endocrine and epithelial cell features occur within the same cell; i.e. amphicrine carcinoma. Herein, we report the case of an 80-year-old female patient who presented with melena, and who, on biopsy was diagnosed as amphicrine carcinoma that was mismatch repair deficient (MMRd) with loss of MLH1/PMS2 nuclear expression by immunohistochemistry. The histological and immunohistochemical findings of this rare entity are presented with review of pertinent literature.