IgG4関連消化管病変

Immunoglobulin G4-related Gastrointestinal Disease

要旨●IgG4関連疾患と同様の機序が示唆される，IgG4関連消化管病変の疾患概念は確立されていない．IgG4関連消化管病変として報告されている例は，主に粘膜下に多数のIgG4陽性形質細胞浸潤と線維化を生じて，胃や食道に著明な壁肥厚を呈する例と，胃や大腸などに生じたIgG4が関連した偽腫瘍の2つのタイプに分かれる．IgG4関連消化管病変と診断するには，多数のIgG4陽性形質細胞浸潤を伴った腫瘤や壁肥厚の形成に加えて，花筵状線維化や閉塞性静脈炎などの特徴的な病理組織像，高IgG4血症や，ほかのIgG4関連疾患の合併などを含めて判断する必要がある．固有筋層内への筋状を呈したリンパ球と形質細胞の密な浸潤と，粘膜固有層深部における形質細胞の集簇は，本病変の特徴的な病理所見の可能性がある．

　The concept of IgG4-GID（immunoglobulin G4-related gastrointestinal disease）is yet not established. Reported cases of IgG4-GID were divided into gastrointestinal lesions showing marked thickening of the stomach wall and esophagus consisting of dense fibrosis with abundant infiltration of IgG4-positive plasma cells, which usually present as a submucosal layer, and IgG4-related pseudotumor occurring in the stomach and colon. Nodular formation or wall thickening with abundant infiltration of IgG4-positive plasma cells is essential for the diagnosis of IgG4-GID. However, for the diagnosis, the characteristic histological features, such as storiform fibrosis and obliterative phlebitis, elevated serum IgG4 levels, and other IgG4-related diseases should be fully considered. Strands of dense lymphoplasmacytic infiltration within the thickened muscularis propria and aggregation of plasma cells in the deeper mucosa might also be the characteristic histological features of IgG4-GID.