Fig. 4From: Semiquantitative 18F-FDG PET/CT in monitoring glucocorticoid response of immunoglobulin G4-related effusive constrictive pericarditis: a case reportPericardial biopsy. (a) The tissue section of the pericardium showing diffuse pericardial thickening with dense plasma cell infiltration. (b) Immunohistochemistry of IgG. (c) Immunohistochemistry of IgG4 demonstrated > 50 IgG4-positive cells per high-power field with an IgG4/IgG ratio of > 20%, consistent with IgG4-related disease. IgG: immunoglobulin G, IgG4: immunoglobulin G4Back to article page