High-Grade Mixed Adenoneuroendocrine Carcinoma in the Cecum: A Case Report.

Gastrointestinal neoplasms with an exocrine and a neuroendocrine component are rare. Such neoplasms are called "mixed adenoneuroendocrine carcinomas" (MANECs) according to the most recent World Health Organization classification of gastrointestinal tract neoplasms. MANECs have no specific findings that distinguish them from pure adenocarcinomas. In addition, the optimal management strategy of MANECs is largely unknown. We describe the case of a 32-year-old man with dizziness and abdominal bloating. A cecal mass was suspected based on an image study done at a local clinic. We evaluated the cecal mass by using colonoscopy, contrast enhanced computed tomography of the abdomen, positron emission tomography-computed tomography, and laboratory studies. The patient underwent a right hemicolectomy and adjuvant chemotherapy. The final histopathological diagnosis was a high-grade MANEC of the ascending colon, tumor stage T3N2M0.