菅野 敦

BACKGROUND: Immunoglobulin G4 (IgG4)-related gastrointestinal diseases (IgG4-GID) are becoming increasingly recognized. However, few cases have been reported, and the disease concept is not yet well established. This study aimed to elucidate the clinical features of IgG4-GID. METHODS: This nationwide multicenter retrospective study collected 37 cases of IgG4-GID, which were classified and analyzed based on the pathological findings and the presence or absence of IgG4-related diseases in other organs. The pathological possibility of IgG4-GID was classified as definite, highly likely, probable, or unlikely based on the presence of typical pathological findings, number of IgG4-positive cells, and adequacy of histological evaluation. RESULTS: Thirteen patients were classified as unlikely to undergo pathological evaluation. Among the remaining 24 cases, 20 had other organ involvement (pathologically definite, n = 8; highly likely, n = 6; probably, n = 6). The four cases without the involvement of other organs were classified as definite. After defining definite and highly likely cases, 18 cases of IgG4-GID were identified. The most commonly affected organs were the stomach (n = 12) and the duodenum (n = 6), with one case involving both. Endoscopic findings most frequently showed ulcers (n  = 7), followed by submucosal tumor (SMT)-like morphology (n  = 6). Treatments included surgery (n  = 8; SMT-like cases), steroids (n  = 2), and proton pump inhibitors or potassium-competitive acid blockers (n  = 3), with all cases showing improvement. CONCLUSIONS: IgG4-GID exhibits characteristic pathological findings and various endoscopic features. Although many patients respond to treatment, some undergo surgery; thus, increased awareness may help avoid unnecessary surgeries.