生検によってⅠs型からⅡa＋Ⅱc型に変化した早期大腸癌の1例

Early Colonic Cancer of the Protruding Type Transforming into the Superficial and Depressed Type, Report of a Case

要旨　患者は76歳，女性．主訴はなく，本人の希望で当院外来で施行された注腸X線検査，大腸内視鏡検査および生検病理診断で横行結腸に10mm大のⅠs型早期大腸癌が認められた．術前のマーキング目的で，再度大腸内視鏡検査を施行したところ，前回認められたⅠs型腫瘍は脱落し，表面陥凹型に変化していた．切除標本の病理学的検索では深達度mのⅡa＋Ⅱc型早期大腸癌であった，生検を行わなくても，固い糞便と腸管の蠕動による機械的刺激で自然に脱落した可能性が示唆され，大腸癌の自然史を考えるうえで貴重な症例と思われる．

　A Protruding lesion of an 76-year-old woman was observed in the transverse colon during screening examination of barium enema. Initial colonoscopic examination with biopsy diagnosed it as Ⅰs type cancer. Sixteen days later, the lesion had minimal reduction in size and transformed into the superficial and depressed type. In the resected specimen, there was a type Ⅱa ＋ Ⅱc lesion measuring 7 × 6 mm in size. It was well differentiated adenocarcinoma, limited to the mucosa. This case was interesting for considering the natural course of colonic cancer.