終末回腸に輪状病変を来した顕微鏡的多発血管炎の1例

Microscopic Polyangiitis Presenting with Circular Lesions in the Terminal Ileum, Report of a Case

要旨●患者は40歳代，男性．腹痛を主訴に受診し，炎症反応高値と尿蛋白・尿潜血陽性を認め入院となった．腹部CT検査で終末回腸に限局した腸管壁の肥厚がみられた．大腸内視鏡検査では，終末回腸に限局して輪状病変の多発と浮腫がみられた．輪状病変は潰瘍とうろこ模様で構成されていた．小腸の生検組織では血管炎に合致する所見であった．急速進行性糸球体腎炎の合併があり，顕微鏡的多発血管炎（MPA）と診断した．プレドニゾロン（PSL）40mg/dayに加えて，シクロホスファミド（CPA）50mgの隔日投与にて軽快した．MPAは多くの臓器を冒し，消化器症状もみられるが，小腸病変を内視鏡的に観察された報告は自験例を含めて3例と少なく，いまだ内視鏡診断は確立していない．小腸に輪状病変や帯状潰瘍を認めた場合，頻度は低いがMPAを含む抗好中球細胞質抗体（ANCA）関連血管炎を鑑別に入れる必要がある．

　A 40-year-old man presented to our hospital with a complaint of abdominal pain. Inflammatory markers were high ; urine protein and occult hematuria were present. An abdominal computed tomography scan showed segmental wall thickening in the terminal ileum. Colonoscopy revealed multiple circular lesions with ulceration and erythema. Findings on biopsy specimens were consistent with vasculitis. There was concomitant rapidly progressive glomerulonephritis. Therefore, microscopic polyangiitis was diagnosed. Symptoms improved after alternate-day administration of 40mg of prednisolone and cyclophosphamide.

　Microscopic polyangiitis targets several organs, including the digestive tract. However, the endoscopic findings have not yet been established. To date, there have been three reported cases, including this case, in which small intestinal lesions were observed endoscopically. These studies suggest that when circular and girdle ulcers are recognized in the small intestine, antineutrophil cytoplasmic antibody-associated vasculitis, including microscopic polyangiitis, should be considered during differential diagnoses.