興味深い内視鏡像を呈したcollagenous colitisの1例

Collagenous Colitis in which Interesting Endoscopic Images were Observed, Report of a Case

要旨　6か月前に狭心症を発症しアスピリン，チクロピジン，ランソプラゾールなどを服用中の64歳，女性が慢性下痢で当科外来を受診し，大腸内視鏡検査が行われた．盲腸では軽度の血管透見低下がみられる程度であったが，大腸の他部位では血管透見低下とともに，インジゴカルミン撒布により不規則な粘膜模様と，腸管長軸方向に走るひび割れ様の浅い線状溝が多数観察された．またS状結腸から直腸では背景粘膜の白色調変化によって通常観察でも縦走する浅い線状溝が観察され，これらの所見は血管透見像と対照的に管腔の伸展に伴い不明瞭化した．大腸の各区分より生検を行い，被蓋上皮下の膠原線維束（20～40μm），上皮内および粘膜固有層に単核球を主体とし，好酸球を交えた炎症細胞浸潤，被蓋上皮の変性，剥離が認められた．これらの所見より，collagenous colitisと診断した．症状はランソプラゾールを変更して1か月で改善した．自験例でみられた線状溝の所見はこれまでに報告がみられず，本症の新たな内視鏡像の可能性がある．

　A 64-year-old female patient under medications（aspirin, ticlopidine, lamsoprazole and so on）for angina pectoris during the past six months visited our outpatient clinic complaining of chronic diarrhea, so colonoscopy was performed. In the cecum, only indistinct vascular transparency was observed. In the other parts of the large intestine, irregular fine network patterns and crack-like shallow, linear grooves along the longitudinal axis were also observed with indigo carmine spraying. In the rectum and sigmoid colon, the linear grooves were discernible by conventional observation by whitish discoloration of mucosa. These findings became obscure as the lumen was distended by insufflation of air in contrast to vascular transparency. Mucosal biopsies taken from each segment of the large intestine showed deposition of a collagen band, 20 to 40μm in thickness, beneath the surface epithelium. Inflammatory cell infiltration of mainly mononuclear cells and numerous eosinophils in the lamina propria, and degeneration and exfoliation of surface epithelium were also observed. The diagnosis of collagenous colitis was made in consideration of these histological findings. Administration of lansoprazole was discontinued, followed by amelioration of diarrhea in one month. Linear grooves observed in this case have not been reported within previous literature, but, these findings may be a clue to the diagnosis of collagenous colitis.