Neuroendocrine Tumor Arising From Meckel's Diverticulum Unexpectedly Diagnosed After Diverticulectomy and in Which Multiple Lymph Node Metastases Were Found After Reoperation: A Case Report.

A 47-year-old man with progressive anemia possibly due to digestive tract bleeding was referred to our hospital. Contrast-enhanced computed tomography of the abdomen showed a 2-cm tumor lesion arising near the small intestine. Enteroscopy revealed a 3-cm submucosal tumor at the ileum. A gastrointestinal stromal tumor of the small intestine was suspected, and the patient underwent surgery. During the operation, a diverticulum approximately 60 cm orad to the terminal ileum and a tumor at the top of the diverticulum were observed. Considering the location, Meckel's diverticulum was suspected. No lymphadenopathy was present in the mesentery. Laparoscopy-assisted resection of the diverticulum without lymph node dissection was performed. The histological diagnosis of the tumor was a well-differentiated neuroendocrine tumor. Given the possibility of lymph node metastasis, we performed a second operation to remove the small intestine and lymph nodes. Histologically, 7 of the 18 dissected lymph nodes were metastatic. The postoperative course was uneventful, and the patient survived without tumor recurrence for another 2 years 8 months. Neuroendocrine tumors of Meckel's diverticulum are aggressive. Therefore, small intestinal resection along with lymph node dissection might be necessary as part of the surgical strategy.