虚血性腸病変の病理診断

Pathological Diagnosis of Intestinal Ischemic Lesions

要旨●慢性期の特発性虚血性小腸炎の肉眼的特徴は境界明瞭な全周性区域性潰瘍による求心性管状狭窄で，病理組織学的に潰瘍底は血管に富む肉芽組織で裏打ちされ，粘膜下層を中心とする線維筋症と線維化は高度である．特発性虚血性大腸炎は一過性型が多く，急性期の生検では粘膜内に種々の程度の出血，間質の好酸性化，腺管上皮細胞の変性・壊死・脱落，粘膜深層の小血管にフィブリン血栓などを認める．潰瘍を形成した症例では慢性期に結腸紐に沿う2〜3条の縦走性線状潰瘍やその瘢痕がみられるものが多い．病理組織学的に開放性潰瘍底は血管に富む肉芽組織で裏打ちされ，瘢痕部は比較的強い線維筋症と線維化を示し，壁全層に担鉄細胞が出現する．閉塞性腸炎は特に癌による閉塞ないし狭窄に伴ってその口側腸管に発生する出血性，潰瘍性病変で，その肉眼的，病理組織学的特徴は特発性虚血性大腸炎のそれと酷似する．腸間膜静脈硬化症は組織学的に静脈壁の著明な線維性肥厚と石灰化，粘膜固有層における著明な膠原線維の血管周囲性沈着，主として粘膜下層の小血管壁への泡沫細胞の出現などの所見がみられる．

　The macroscopic characteristic of chronic phase and stricture forming idiopathic ischemic enteritis is a circular segmental ulcer with clear borders. Histologically, the open ulcer presents highly vascular granulation tissue, severe fibromusculosis and fibrosis, mainly in the submucosa, and hemosiderin deposition on the tissue wall.

　Idiopathic ischemic colitis is generally of the transient type, and biopsy specimens in the acute phase demonstrate varying degrees of hemorrhage and interstitial eosinophilization in the mucosa, as well as degeneration, necrosis, and desquamation of the surface epithelial cells, and fibrin−thrombi in the capillaries of the deeper portion of the mucosa.

　Many cases with ulcers have formed 2−3 longitudinal linear ulcers along the tenia coli, and their scars are often observed during the chronic phase.The pathological finding are similar to those of idiopathic ischemic enteritis.

　Obstructive colitis is a hemorrhagic and ulcerative lesion occurring in the proximal intestinal tract due to obstruction or stenosis, especially due to cancer. Additionally, its gross and histological characteristics closely resemble those of idiopathic ischemic colitis.

　Idiopathic mesenteric phlebosclerosis is histologically characterized by marked venous wall fibrous thickening with calcification, collagenous deposition around the mucosal blood vessels, and foamy macrophages within the submucosal small vessel wall.