Immunoglobulin G4–related multiple systemic aneurysms and splenic aneurysm rupture during steroid therapy

Summary Immunoglobulin G4 (IgG4)–related disorders in various organs have recently been described, but multiple systemic aneurysms have not yet been reported. Here, we present a 68-year-old Japanese man with multiple systemic aneurysms and tumor-forming pericoronary arteritis who was undergoing low-dose corticosteroid therapy. Elevated serum IgG4 (2390 mg/dL) and IgG4-positive plasmacyte infiltration in the salivary glands led to a diagnosis of IgG4-related disease. High-dose corticosteroid therapy was initiated, whereupon the inflammatory lesions shrank. However, the large, well-developed common hepatic aneurysm and splenic aneurysm did not change. Our patient died of splenic aneurysm rupture in the sixth month of treatment. The autopsy revealed IgG4-positive plasmacyte infiltration in the coronary wall and a thinned splenic aneurysm wall. This case suggests that early high-dose corticosteroid therapy may be necessary for the treatment of IgG4-related cardiovascular disorders. A minor salivary gland biopsy might facilitate the early diagnosis of IgG4-related disease even if 18 F-fluorodeoxyglucose positron emission tomography provides no inflammatory findings.