Abstract
A 39-year-old man was admitted with a chief complaint of an abnormal fecal occult blood test. The endoscopic view showed a submucosal tumor, 5 mm in diameter, located in the distal rectum. After an endoscopic mucosal resection (EMR), the condition was histopathologically diagnosed as a neuroendocrine carcinoma (NET), G1. The tumor had negative vertical and horizontal margins, but there was minimal lymphatic invasion. He underwent additional surgery. Histological examination of the surgical specimen showed no residual NET component in the rectum and lymph node metastases at station 251 (Japanese Classification of Colorectal Carcinoma, 8th Edition). The patient continues to be followed. For tumors smaller than 6 mm in size, almost all cases in this subgroup have no lymph node metastases. As seen in this case, for a rectal carcinoid with lymphatic invasion, additional surgery or careful follow-up is necessary.
