特殊な内視鏡所見を呈した早期直腸癌の1例

Early Rectal Cancer with Atypical Endoscopic Findings, Report of a Case

要旨●患者は60歳代，男性．直腸に病変を認め当院紹介となった．全大腸内視鏡検査を施行し，直腸S状部に径20mm大のIp病変を認めた．色調は赤色調，表面は比較的平滑な部分と凹凸が目立つ部分の2つの異なった構造を認めた．拡大所見では間質は広く，多様な形状の腺管開口部を認めた．上皮性病変と判断したが腫瘍・非腫瘍の判断は困難であり，診断的治療目的に内視鏡的粘膜切除術（EMR）を施行した．病理診断はadenocarcinoma in adenoma ; carcinoma component，well to moderately differentiated adenocarcinoma（tub1＋tub2） ; depth，m（pTis） ; ly0 ; v0 ; adenoma component，tubular adenoma with moderate atypia（low grade） ; margin，negativeであった．拡大所見も含め，従来の管状腺腫，早期癌とは異なった内視鏡所見を呈し，非常に興味深い病変と考えた．

　A 60-year-old male underwent colonoscopy because of a positive fecal occult-blood test. A reddish Ip lesion with a diameter of approximately 20mm and two compartments on the surface was observed in the rectosigmoid. Magnified endoscopic view showed atypical surface structures in both compartments.

　Although the lesion was considered to be epithelial, a definitive diagnosis pertaining to the cancerous nature of the lesion was difficult. Therefore, an endoscopic mucosal resection was performed.

　Pathological diagnosis confirmed a well-to-moderately differentiated adenocarcinoma with the following characteristics：（tub1,2） ; depth, m（pTis） ; ly0 ; v0 ; pHM0 ; and pVM0. The adenocarcinoma was also revealed to be tubular with low-grade dysplasia.

　Endoscopic findings showed that the lesion was different from conventional tubular adenomas and early cancers ; therefore, it was considered to be of interest.