A Case of an 8-mm Rectal Neuroendocrine Tumor with Lymph Node Metastasis

Abstract

A 62-year-old woman, who suffered from abdominal pain, was examined by colonoscopy as an outpatient in the Department of General Internal Medicine in our hospital. The colonoscopy indicated a tumor in the lower rectum, thereby an endoscopic mucosal resection was performed on the same day. Pathological findings indicated a neuroendocrine tumor (NET) G1 of the rectum according to the World Health Organization classification. The tumor was 8 mm in diameter and confined to the submucosal layer. There was no evidence suggestive of lymphatic or venous invasion. The surgical stump was negative, but pathological evidence suggested that the tumor was close to the stump. She was referred to our department for surgical treatment. Thus, we performed a laparoscopic super low anterior resection with covering ileostomy. Indeed, pathological analysis of the resected lesion showed lymph node metastasis (#251 2/8), and the final diagnosis was T1aN1M0 stage III B (UICC 8). The standard guideline for the treatment of NETs of less than 10 mm recommends either endoscopic resection or trans anal resection since this size of rectal NET with metastasis is very rare. This clinical case presents a unique figure that a small NET (<10mm) had lymph node metastasis.