A Rare Case of Mixed Adenoneuroendocrine Carcinoma of the Ileocecal Valve

Mixed adenoneuroendocrine carcinoma (MANEC) is an uncommon neoplasm with uncertain pathophysiology. In order to be classified as MANEC, the tumor must contain at least 30% neuroendocrine cells and 30% adenocarcinoma. The standardization of MANEC treatment has historically been difficult due to the lack of diagnostic histological classification. In 2010, the World Health Organization (WHO) finally recognized this uncommon condition as a specific colon cancer entity in the hopes of better specifying treatment options in the future. We present a case of high-grade MANEC of the cecum with metastasis in 3/10 lymph nodes to further characterize the diagnostic modalities and treatment options of the disease. MANECs only account for 3%-9.6% of all colorectal cancers and only eight cases have been reported in the cecum to date, making the following case report exceptionally rare.