Significant pericardial involvement of immunoglobulin G4-related disease.

A 60-year-old woman was hospitalized with cardiac tamponade due to effusive pericarditis presenting with significant thickening of the pericardium. Serum immunoglobulin G4 (IgG4) level was elevated to 1,800 mg/dL, and an open biopsy specimen from the pericardium revealed massive infiltration of lymphocytes and IgG4-positive plasma cells. She had experienced adenopathies in the lacrimal and parotid glands 6 months earlier, and was diagnosed as having IgG4-related Mikulicz's disease by similar cell infiltration in the salivary gland biopsy. The significant involvement of the pericardium as a manifestation of IgG4-related disease is described, as well as the successful treatment with oral corticosteroids.