免疫異常状態における消化管炎症性病変の臨床像と画像診断

Gastrointestinal Manifestations in Immuno-dysregulatory Conditions

要旨　免疫不全と移植片対宿主病（GVHD）における消化管病変の臨床的特徴を概説した．先天性免疫不全の中でも，リンパ球機能低下における消化管病変の報告は少ないが，その多くは小腸の原虫・寄生虫感染症とそれによる吸収不良症候群である．これに対し，慢性肉芽腫症や糖原病などの好中球機能低下症では慢性の大腸病変が発生し，臨床像や画像所見は特発性慢性炎症性腸疾患に類似している．後天性免疫不全の中でもHIV感染症とHTLV-1感染症では原虫・寄生虫感染による小腸病変が認められる．また，後天性免疫不全では真菌感染による食道病変とウイルス感染による潰瘍性病変に遭遇することが多い．一方，医原性免疫過剰反応であるGVHDでは多彩な病変が消化管のいずれの部位にも発生するが，その基本は腺窩上皮の浮腫および粘膜脱落と考えられる．免疫異常状態における消化管病変の画像診断に際しては，消化管感染症の病態を熟知しておく必要がある．

　We reviewed radiographic and endoscopic features of gastrointestinal (GI) involvement in immunodeficiency diseases and graft-versus-host disease (GVHD). Although GI involvement of primary immunodeficiency with lymphocyte defect has been described to some extent, protozoal or parasitic infestations accompanied by malabsorption are major GI manifestations. In contrast, chronic colitis frequently occurs in primary leukocyte dysfunction such as chronic granulomatous disease and glycogen storage disease. The radiographic and endoscopic findings of chronic colitis mimic those found in inflammatory bowel diseases. Protozoal and parasitic infestations are also the major small intestinal involvement in HIV or HTLV-1 infection. In addition, fungal infection of the esophagus and GI ulcers induced by viral infection occur in cases of acquired immunodeficiency. In GVHD, heterogeneous gastrointestinal lesions are found anywhere within the GI tract. However, mucosal edema and sloughing are characteristic of the disease. There seems to be a need to interpret radiographic and endoscopic features of individual GI infections, because immuno-dysregulatory conditions are predisposed to the infection.