Abstract
A 75-year-old man visited our hospital after noticing a 30-mm mass in the left lower quadrant. A solid tumor showing enhancement on contrast-enhanced computed tomography (CT) and hypointensity on both T1- and T2-weighted magnetic resonance imaging (MRI) was found in the mesentery of the small intestine. The tumor was not continuous with the small intestine and was diagnosed as either gastrointestinal stromal tumor (GIST) or malignant lymphoma, and surgery was performed. The tumor was thought to be a metastasis to lymph nodes in the mesentery of the small intestine, and because four small lesions were palpable in the small intestine near the tumor during examination of the entire small intestine, small intestinal resection and lymph node dissection were performed. The pathological diagnosis was multiple small intestinal carcinoid tumors (n=4 ; neuroendocrine tumor (NET)) with lymph node metastases.
Small intestinal NET is rare in Japan, and its preoperative diagnosis is difficult. However, cases have been reported in which it was detected due to the large size of metastatic lymph nodes, as in the present case. Small intestinal NET may occur at multiple sites, and it was considered important to perform a thorough search for small intestinal lesions before and during surgery.
