好酸球浸潤が目立つ原因不明の慢性大腸炎の1例

Undetermined Chronic Colitis with Prominent Eosinophilic Infiltration, Report of a Case

要旨　患者は26歳，女性．腹痛，下痢，血便のため入院した．大腸内視鏡検査にて，盲腸からS状結腸にびまん性の顆粒状粘膜がみられ，生検にて著明な好酸球浸潤を認めた．病変は大腸に限局し，上部消化管と小腸には異常を認めなかった．好酸球性胃腸炎におけるTalleyらの診断基準および木下らの診断指針（案）から好酸球性腸炎（大腸炎）の可能性を考慮したが，肉眼的に発赤，浮腫，びらんではなく顆粒状粘膜が主体であること，病理組織学的に好酸球以外の炎症細胞が高度かつびまん性に浸潤していること，好酸球の上皮内浸潤像が観察されないことから，いわゆる好酸球性胃腸炎とは異なる疾患と考えられた．アレルギー性腸炎の可能性は否定できないが，各種食物アレルゲン検査は陰性であった．大腸に好酸球が浸潤する原因は多彩であり，特に炎症性腸疾患は経過を経て典型例に移行することもあることから，診断には慎重な配慮が必要と考えられた．

　A-26-year old woman was admitted to our hospital with abdominal pain, diarrhea and hematochezia. Colonoscopy revealed diffuse granular mucosa from cecum to sigmoid colon, and the biopsy specimens demonstrated prominent eosinophilic infiltration. The diseased area was limited to the large intestine with neither endoscopic nor pathological findings both in upper gastrointestinal tract and the small intestine. Eosinophilic colitis could be suggested according to the diagnostic criteria（Talley et al. and Kinoshita et al.）. However, the disease other than so-called eosinophilic colitis was considered because macroscopic findings are granular mucosa but not erythema, edema and erosion, and pathological findings show a severe and diffuse inflammatory infiltrate without an intraepithelial infiltrate. Although allergic colitis could not be denied, various food allergic tests were all negative. Careful consideration is required in the diagnosis of colitis with an eosinophilic infiltrate with reference to various disorders. Especially, undetermined colitis could progress to typical inflammatory bowel disease.