表層粘膜上皮直下に帯状膠原線維沈着を伴った静脈硬化性大腸炎の1例―膠原線維の免疫組織化学的検討を中心に

Phlebosclerotic Colitis with a Thickened Collagen Layer beneath the Surface Epithelium─Immunohistochemical Study for Collagen, Report of a Case

要旨　症例は68歳，女性．主訴は右側腹部痛と水様性下痢．腹部CTと大腸内視鏡検査，生検で回盲部から横行結腸に静脈硬化性大腸炎の所見を，さらに全大腸の表層粘膜上皮直下に帯状膠原線維を認めた．異常沈着した膠原線維を免疫組織化学的に検索した結果，帯状膠原線維はIV型コラーゲン陰性，テネイシン陽性であった．一方，血管周囲性の膠原線維はIV型コラーゲンに血管壁内で陽性，血管周囲で陰性，テネイシンには両者で陰性であった．本例の帯状膠原線維の性状はcollagenous colitisのそれと同じであったが，静脈硬化性大腸炎では沈着した膠原線維を検討した報告がなく，collagenous colitisの合併症例か否かについての確証は得られなかった．

　A 68-year-old woman was admitted to our hospital because of right abdominal pain and watery diarrhea. We made a diagnosis of phlebosclerotic colitis in the cecum, the ascending colon and the transverse colon with findings of abdominal computed tomography, colonoscopic examination and biopsy specimens showing perivascular fibrosis. In addition, the biopsy specimens showed a band-like collagen layer just beneath the surface epithelium extending from the ileocecum to the rectum. We immunohistochemically analyzed the collagen tissues abnormally deposited in different ways and ranges. The band-like collagen layer was positive for tenascin and negative for collagen type IV. While the perivascular collagen was negative for tenascin, immunoreactivity of collagen type IV was prominent for the collagen within the blood vessel walls but not present around the blood vessels. We could not determine whether this case should be diagnosed as phlebosclerotic colitis complicated by collagenous colitis or not, as immunoreactivity for collagen deposited in phlebosclerotic colitis had never been examined.