3)移植片対宿主病（graft-versus-host disease ; GVHD）

Graft-versus-host Disease (GVHD) of the Gut

　同種造血幹細胞移植後の急性GVHDは主に皮膚，肝臓，消化管に起こる．消化管には，病理組織学的にリンパ球の浸潤，腺管のapoptosis，腺管の脱落が生じる．上部消化管急性GVHDの症状は食思不振，嘔気，嘔吐，吐血である．胃の内視鏡所見は前庭部に多く，発赤，びらん，浮腫，粘膜脱落，びまん性出血で，十二指腸では発赤，びらん，浮腫，Kerckringひだの消失，顆粒状粘膜，粘膜脱落，びまん性出血である．初期または軽度な場合，いわゆる表層性胃炎，びらん性胃炎，十二指腸炎で特異的なものではない．急性GVHD腸炎の症状は水様下痢，腹痛で内視鏡所見は，血管透見不良，白色調粘膜，びらん，浮腫，粘膜脱落，潰瘍である．高度の消化管急性GVHDの内視鏡像はびまん性の粘膜脱落を来し，他疾患ではみることができない特異的な所見を示す．

　Acute GVHD after allogenic bone marrow transplantation involves the skin, liver, and GI tract. The histological findings in the GI tract are lymphocyte invasion into the mucosal epithelium, apoptosis of the glandular epithelium, and decrease in the number of glands. Acute upper GI tract GVHD symptoms are appetite loss, nausea, vomiting and hematemesis. Endoscopic findings are redness, erosions, edema, sloughing of the mucosa and, in acute gastric GVHD, diffuse bleeding. In acute duodenal GVHD, the findings are redness, erosions, edema, loss of Kerckring's fold, granular mucosa, sloughing of the mucosa, and diffuse bleeding. Early or mild acute GVHD in the upper GI tract presents non-specific findings such as superficial gastritis, erosive gastritis and duodenitis. Acute GVHD colitis symptoms are watery diarrhea and abdominal pain. Endoscopic findings of acute GVHD colitis are indistinct vascular pattern, white mucosa, erosions, edema, sloughing of the mucosa and ulcers. The specific endoscopic finding of severe acute GVHD in the GI tract is diffuse sloughing of the mucosa, which is never seen in other diseases.