狭窄を来す小腸疾患の診断─病理診断の立場から

Pathology of Stenotic Lesions of the Small Intestine

要旨●小腸狭窄を来す疾患として，癌，悪性リンパ腫，Crohn病，狭窄型虚血性小腸炎について，その肉眼形態と病理組織学的所見について概説した．癌は上皮性変化を伴う高度な輪状狭窄を示し，病理組織学的に癌の浸潤に伴う高度な線維性間質反応が伴う．一方，悪性リンパ腫は間質反応の少ない腫瘍細胞の充実性増殖から壁が肥厚し，浅い潰瘍と幅の狭い輪状狭窄を示す．Crohn病は腸間膜付着側に一致した縦走潰瘍から偏側性狭窄を来し，しばしば裂孔性の深くて幅の狭い潰瘍を伴う．狭窄型虚血性小腸炎は全周性区域性潰瘍を伴う管状狭窄を示す．組織学的には潰瘍底に血管に富む肉芽組織と粘膜下層の高度な線維筋症と線維化，比較的強い慢性炎症細胞浸潤を伴う．

　Here we describe the histopathological features of small intestinal stenotic diseases, such as cancer, malignant lymphoma, Crohn's disease, and ischemic stenosis. Neoplasms typically show severe annular stenosis with epithelial dysplasia, and histologically, a severe desmoplastic reaction accompanied by the invasion of cancer cells is observed. On the other hand, in malignant lymphoma, the small intestinal wall is markedly thickened by the proliferation of lymphoma cells, with small desmoplastic reaction, and shows shallow ulcers with annular stenosis. Crohn's disease results in lateral stenosis with longitudinal ulcer on the mesenteric site and is often accompanied by deep and narrow fissuring ulcers. Ischemic stenosis of the small intestine is characterized by concentric tubular stenosis involving the entire circumference and segmental ulcers. Histologically, vascular-rich granulation tissue, marked fibromusculosis, and fibrosis are observed in the submucosa, accompanied by a relatively severe chronic inflammatory infiltrate.