リンパ節転移を伴う6mm大の直腸高分化神経内分泌癌に対して腹腔鏡補助下低位前方切除術を施行した1例

Laparoscopy-assisted low anterior resection for 6mm well differentiated neuroendocrine carcinoma of the rectum with lymph node metastasis

◆要旨：患者は63歳，男性．検診で大腸内視鏡検査を行い，肛門縁より 6cm の直腸 Rbに粘膜下腫瘍を指摘された．大腸超音波内視鏡所見では2～3層を主座とする径11mmの腫瘍であり，生検で高分化神経内分泌癌（well differentiated neuroendocrine carcinoma；以下，WDEC）と診断された．CT検査で明らかな他臓器転移を認めなかった．直腸WDECの診断で腹腔鏡補助下低位前方切除術を施行した．切除標本では径6mmの直腸WDECであり，病理組織学的に粘膜下層までの浸潤と，「大腸癌取扱い規約 第7版」における251番リンパ節への転移を認めた．微小WDECであってもリンパ節転移の可能性があり，腹腔鏡下手術によるリンパ節郭清を伴う腸管切除は低侵襲で有用であると考えられた．

　We report a patient with well differentiated neuroendocrine carcinoma （WDEC） with lymph node metastasis who underwent laparoscopy-assisted low anterior resection. A 63-year-old man with submucosal tumor in the lower rectum 6 cm from the anal verge was diagnosed with a rectal WDEC by colonoscopy. Endoscopic ultrasound showed a tumor 11 mm in diameter, invading the submucosal layer. Computed tomography showed no signs of metastasis. A laparoscopy-assisted low anterior resection with lymph node dissection was performed, assuming a diagnosis of rectal WDEC. Histopathological examination of the surgical specimen revealed a WDEC, 6 mm in diameter, invading the submucosal layer of the rectum with metastatic lymph node at station 251 （Japanese Classification of Colorectal Carcinoma, 7th Edition）. The patient is doing well 15 months after the surgery without any signs of recurrence. Laparoscopic surgery is considered to be a good surgical approach for this type of tumor with lymph node metastasis.