A Small Rectal Neuroendocrine Tumor of Less Than 5mm with Lymph Node Metastasis

Shoji Kokubo, Shinobu Ohnuma, Hideyuki Suzuki, Hirofumi Imoto, Akihiro Yamamura, Hideaki Karasawa, Atsushi Kohyama, Takeshi Aoki, Kazuhiro Watanabe, Naoki Tanaka, Hiroaki Musha, Fuyuhiko Motoi, Takashi Kamei, Takeshi Naitoh, Michiaki Unno

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According to the treatment guideline for rectal neuroendocrine tumor(NET), tumor with a diameter ofC10mm should be resected endoscopically, while tumor with a diameter of>10mm should be resected surgically with lymph node dissection. We experienced a case of a rectal NET with a diameter of 5mm with lymph node metastasis. A 69-year-old man underwent colonoscopy for positive fecal occult blood test. The colonoscopy revealed a submucosal tumor(SMT)with a diameter of 5 mm in the lower rectum. An endoscopic mucosal resection(EMR)was performed after SMT was diagnosed as NET by biopsy. Histopathological findings were NET-G1, 4.5×2.5 mm, v(+), ly(+). Then, laparoscopically assisted rectal resection with D2 lymph node dissection was performed. In histopathological examination, no tumor residue was observed in the specimu; however, a regional lymph node metastasis was detected. Risk factors of lymph node metastasis with rectal NET are a diameter of>10 mm, recessed or ulcerated surface, and lymphovascular invasion. However, we have to keep in mind that lymph node metastasis may occur even in small rectal NET with a diameter of ≤10mm.

Original languageEnglish
Pages (from-to)1985-1987
Number of pages3
JournalJapanese Journal of Cancer and Chemotherapy
Issue number13
Publication statusPublished - 2018 Dec 1


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