特発性腸間膜静脈硬化症と鑑別を要した直腸動静脈奇形の1例

An Arteriovenous Malformation of the Rectum, Report of a Case

要旨　患者は52歳，女性．12歳時より下血を繰り返していた．52歳時に精査目的にて当科入院．下部消化管内視鏡で直腸粘膜は暗赤色で静脈のうっ滞がみられた．腹部CTでは直腸間膜の著明な肥厚および石灰化が認められた．血管造影では上直腸静脈の造影効果は乏しく，明らかな動静脈奇形の所見はみられなかった．以上より，特発性腸間膜静脈硬化症が最も疑われた．保存的治療に反応しない慢性的な下血症状に対し，腹腔鏡補助下超低位前方切除と回腸人工肛門造設術を施行した．病理組織検査にて直腸全層に拡張した血管が認められた．血管壁は静脈様，動脈様構造が様々な形で互いに吻合しており，動静脈奇形と診断された．若年時に発症し，長年の経過をたどる下血には，動静脈奇形を考慮する必要がある．

　A 52-year-old female who had suffered from unexplained melena since she was 12 years of age was admitted to our hospital. Colonoscopy showed a wine-colored mucosa and venous stasis of the sigmoid colon and the rectum. Computed tomography detected a significantly thickened and calcified mesorectum. Angiography identified a superior rectal vein with hypodense contrast, whereas there was no evidence of any arteriovenous malformaion. These findings before surgery led to the suspiction of idiopathic mesenteric phlebosclerosis. A laparoscopy-assisted super low anterior resection of the rectum with covering stoma was performed to treat the chronic colitis with serious melena. Histological findings revealed diffuse dilated vessels in the rectal tissue specimen, in which both vein-like and artery-like walls were connected with each other. Finally, this lesion was diagnosed as arteriovenous malformation of the rectum. We should keep in mind the possible existence of arteriovenous malformation, when a patient has experienced continuous melena occurring since childhood.