Mixed Neuroendocrine-Non-Neuroendocrine Neoplasm (MiNEN) of the Colon: A Case Report

Here we report a rare case of mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs). A 51-year-old lady with no known family history of malignancies developed this rare type of malignancy without any active gastrointestinal symptoms. However, during a routine health check, physicians noticed a raised Carcinoembryonic Antigen (CEA) level and the patient subsequently was referred to the surgical department for further management. A colonoscopy and CECT abdomen were done and she was electively admitted for a left hemicolectomy operation for a splenic flexure tumour. The histopathological report revealed the tumour is a case of mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) [moderately differentiated adenocarcinoma and neuroendocrine tumour grade 3]. TNM (8th edition, 2016): pT3, pN2 (20/21), pMX. Both resection margins were clear from malignant cells. Colorectal MiNENs, constitute a rare group of gastrointestinal tumours composed of both neuroendocrine and non-neuroendocrine components. Given their non-diagnostic macroscopic features, specific histological features and lack of disease awareness which are responsible for the underestimated incidence and conflicting data. In this case, a multidisciplinary team approach is important in managing patients with this malignancy to achieve the best outcome.