microscopic colitis（collagenous colitis，lymphocytic colitis）の概念

Microscopic Colitis（Collagenous Colitis, Lymphocytic Colitis）: Review and Outline

要旨　CCとLCは類縁疾患で，CCとLCを総称してMCと呼ぶ．MCの年間罹患率（人口10万人対）は8.6～10.0（CC 3.1～4.9，LC 4.4～5.5）である．MCの平均発症年齢は65～68歳，男女比はCC 1：7，LC 1：2.4で，CCにおいて女性優位であるが，LCにその傾向はない．MCの原因として，自己免疫疾患，胆汁代謝異常，腸管感染症，薬剤などが挙げられるが結論は得られていない．MCの患者は対照に比して自己抗体（抗核抗体，抗グリアジン抗体，ASCA）の出現頻度が高く，いくつかの自己免疫疾患との合併が報告されている．MCに関連する薬剤としてNSAIDs，PPI（特にランソプラゾール），SSRI，H₂blocker，チクロピジン，アスピリンなどが挙げられているが，比較対照試験から導き出されたものはNSAIDsとSSRIである．MCの内視鏡所見として大腸粘膜の血管網異常，発赤，浮腫，顆粒状変化，縦走潰瘍などが挙げられるが，MCの約30％（本邦では75％以上）に何らかの内視鏡的異常を認める．顆粒状変化やCB沈着は右側結腸で高頻度に認められる．CCにおける縦走潰瘍は非常に長い線状潰瘍（潰瘍瘢痕）として認めることが多く，潰瘍周辺粘膜に炎症性変化を認めないことが特徴である．この縦走潰瘍とランソプラゾールとの関連性が報告されており，特に本邦ではランソプラゾール服用者の78％に縦走潰瘍を認めるといった報告もある．欧米ではこれほど高い頻度は示されておらず，NSAIDsと縦走潰瘍の関連性を示唆した報告もある．この縦走潰瘍は欧米では横行結腸～右側結腸に多く認めるが，本邦では左側結腸に多く認める．CCと鑑別を要する疾患として，虚血性腸炎，Crohn病，腸管アミロイドーシス，特発性腸間膜静脈硬化症，過敏性腸症候群，感染性腸炎，セリアック病などがある．治療はブデソニドが有効で，予後は総じて良好である．

　CC（collagenous colitis）and LC（lymphocytic colitis）are generally diseases that have affinity with each often and are usually called MC（microscopic colitis）. The incidence rate of MC is 8.6～10.0（CC 3.1～4.9,LC 4.4～5.5）/100,000 populations-years. The median age at diagnosis of MC is 65～68 years old and the male : female sex ratio is 1:7 in CC and 1:24 in LC. Female is preponderant in CC, but LC does not have this tendency. Autoimmune disease, bile acid metabolic disorders, enteric infection, and medication are named as causes of MC, but no conclusive evidence obtained. The patients of MC as compared with has not been controls frequently have the autoantibody（antinuclear antibody, anti-gliadin antibody,ASCA）, and merger with some autoimmune disease is reported. As medicine associated with MC NSAIDs,PPI（Lansoprazole ; LPZ in particular）,SSRI,H₂-blocker, ticlopidine and aspirin are given, but medication arrived at by a case-controlled study is NSAIDs and SSRI.

　The abnormal vascular pattern, redness, edema, a granular change, a longitudinal ulcer in the large intestinal mucosa are listed as endoscopic findings of MC. Some kind of endoscopic abnormality is found in approximately 30％ of MC（more than 75％ in this country）. Granular mucosal change and CB（collagen band）deposition are frequently found in the right colon. A longitudinal ulcer in CC often appears it as a very long linear ulcer（or ulcer scar）, and it is characteristic that ulcer periphery mucosa does not show inflammatory change. The association of longitudinal ulcer with LPZ is reported, and there is a report to show that 78％ of LPZ users have longitudinal ulcer particularly in this country. Such a high frequency is not shown in Europe and America, and there is a report that suggested an association of NSAID and the longitudinal ulcer. This longitudinal ulcer frequently occurs in the transverse colon to the right colon in Europe and America, but frequently occurs in the left colon in this country.

　As diseases that need differentiation from CC, there are ischemic colitis,Crohn's disease, intestinal amyloidosis, idiopathic mesenteric phlebosclerosis, irritable bowel syndrome, infectious enteritis and celiac disease. Budesonide is effective for its treatment, and the prognosis of MC is generally good.