平坦型S状結腸m癌の1例

Flat Type of Intramucosal Carcinoma of the Sigmoid Colon, Report of a Case

要旨　最近大腸早期癌の中でも低い隆起，扁平ないし陥凹型の病変が注目されているが，われわれはS状結腸のⅡcないしⅡb類似の平坦型m癌を経験したので報告する．患者は64歳男性．当院人間ドックにおける一次スクリーニングとしてのS状結腸ファイバースコープにて，肛門縁より28cmの部位にほぼ平坦な限局性発赤病変が発見され，生検の結果腺癌と判明した．S状結腸切除を施行したところ，切除標本では18×12mmのほぼ平坦な発赤病変であり，組織標本では粘膜内に限局した高分化腺癌であった．単発性の平坦ないし陥凹型の早期高分化腺癌は数少ないと思われるが，内視鏡検診の普及などにより今後症例が集積される可能性もあり，大腸早期癌の一型として注目したい．

　A 64-year-old man was admitted to Tokyo Kosei Nenkin Hospital on August 1, 1983, for a periodic health check-up. He was asymptomatic and his fecal occult blood tests were negative. On sigmoidoscopy performed as a routine examination of screening for colorectal cancer, a small and flat erythematous lesion was visualized at 28 cm from the anal verge (Fig. 1). Biopsy specimen was interpreted as an adenocarcinoma. Barium enema demonstrated a suggestive but not definitive lesion (Fig. 2).

　Sigmoidectomy was performed on August 19. The gross specimen revealed slightly depressed erythematous Ⅱc or Ⅱb-like lesion, measuring 18×12 mm (Fig. 3). Microscopically, this small lesion showed a mixture of well-differentiated adenocarcinoma and atypical glands confined to the mucosal layer (Figs. 4 and 5).

　Most of early cancer of the colon and rectum seem to be elevated lesions, but there are several reports of flat or depressive type of adenocarcinoma. It is expected that these Ⅱb or Ⅱc-like early cancer will increase owing to the progress of screening method of colorectal carcinoma.