The frequency of ileal neuroendocrine tumor (NET) is low in Japan, accounting for only 0.6% of all gastrointestinal NETs.
A 53-year-old male was found to have a 5 mm-diameter reddish submucosal tumor (SMT)-like lesion in the terminal ileum by colonoscopy. Histological examination of the biopsied specimen led to the diagnosis of NET. Endoscopic ultrasound (EUS) showed a hypoechoic structure in the second and third layers, and endoscopic submucosal dissection (ESD) was performed. The ESD was regarded as a non-curative resection due to the pathologic finding of lymphatic invasion by immunostaining with D2-40. Therefore, laparoscopic ileal resection with D3 lymph node dissection was performed.
Even Small lesions of ileal NET have been reported to metastasize. During colonoscopy, endoscopists should observe the terminal ileum carefully and biopsy SMT-like lesions intentionally.
