虚血性大腸炎の病理

Pathomorphologic Study of Ischemic Colitis

　虚血性大腸炎は大腸分節に対する血行障害が主因となって起こると推察される疾患である．本症はBoleyら（1963年）¹⁾およびMarstonら（1966年）³⁾の発表以来，1つの独立疾患として注目されるようになり，近年報告例の増加に伴って臨床的，X線学的，内視鏡的および病理学的知見も明らかにされている^{2)4)14)～17)}．しかし，実際には虚血の期間や程度，病変の時期（病期）や病因により種々の病理形態像を呈することが考えられ，また本症がしばしば一過性で経過観察のみのこともあって，その病理形態学的特徴についてはいまだ十分に解明されているとはいい難い．

　われわれは手術的に切除され病理組織学的検索が可能であった虚血性大腸炎10例，および臨床的・X線的に本症と考えられて生検が施行された6例の計16例を経験した．本稿では，これら16例のうち手術例10例を中心に，主として病理形態学的立場から，虚血性大腸炎の肉眼的および組織学的特徴を述べる．

　Ischemic colitis is now well recognized as an established clinical entity. In this paper, 16 patients with this disease were studied pathomorphologically. Sourse of pathologic materials was surgical resection in ten and endoscopic biopsy in six.

　In four cases with this disease in acute phase macroscopic changes were diffuse mucosal homorrhage and irregular open ulcers, Ul-Ⅰ and/or Ul-Ⅱ, having tendency to longitudinal situation and to association with pseudomembrane. The histologic features of these cases consisted of fresh mucosal hemorrhage, degeneration and necrosis of glandular epithelium, open ulcer, and marked submucosal thickening due to prominent edema, hemorrhage, congestion and neutrophilic infiltration.

　Six cases showing ischemic stricture of the bowel presented the lesion made up of one and/or three, long, longitudinal, linear or zonal ulcers, open or healed, along the teniae coli. More than two longitudinal ulcers were characteristic of ischemic colitis in chronic phase. The microscopic appearances were composed of five main pictures as follows; 1) Ulcers of Ul-Ⅱ, 2) Open ulcers floored with vascular granulation tissue characterized by swollen endothelial cells of the capillaries, 3) Prominent fibromusculosis and fibrosis in the submucosa adjacent to the healing ulcers, 4) Presence of many hemosiderin-laden macrophages scattered through the whole thickness of the colon, 5) Slight inflammatory infiltrate consisting mainly of lymphocytes and plasma cells. Among these findings, presence of many hemosiderin-laden macrophages is considered as of particular diagnostic importance.