Primary Mesenteric Neuroendocrine Tumor: A Rare and Unexpected Finding

Abstract Neuroendocrine tumors (NETs) are rare malignancies originating from enterochromaffin cells, with up to 90% arising in the gastrointestinal tract. Those located in the mesentery are usually metastatic, and primary mesenteric NETs are exceedingly rare. We herein report the case of an 82-year-old man referred to general surgery after an incidental mesenteric mass detected on a fluorodeoxyglucose-positron emission tomography (18F-FDG PET-CT) scan performed for the evaluation of a pulmonary lesion. An abdominal computed tomography (CT) scan revealed a 30-mm mass in the mesentery, adjacent to the ileocolic vessels. The patient underwent exploratory laparoscopy and excision of the mass. A histopathological analysis confirmed a well-differentiated NET. The patient was started on octreotide therapy, which continues to date. At 24 months of follow-up, the patient remains asymptomatic. Given the rarity of primary mesenteric NETs and the predominance of metastatic lesions at this site, comprehensive exclusion of other potential primary-tumor sites is of utmost importance.