Clinicopathological features of immunoglobulin G4-related constrictive pericarditis

Constrictive pericarditis (CP) is characterised by scarring fibrosis and a loss of pericardial elasticity, which causes heart failure. IgG4 (immunoglobulin G4)-related disease (IgG4-RD) is a systemic fibro-inflammatory disease characterised by the infiltration of IgG4-immunopositive plasmacytes and high serum IgG4 levels that frequently shape tumorous lesions. Although pericardial involvement of IgG4-RD is rare, with indications of CP, pericardial effusion and irregular masses, the clinical and pathological features remain unclear. In this study, we examined the relationship between CP and IgG4-RD.

Among 35 thick-walled CP cases (histologically pericardial thickening ≥2 mm), eight cases were aetiology identified. Using the diagnostic criteria for IgG4-RD, 11 cases were classified as IgG4-CP, whereas the remainder were considered true idiopathic CP (16 cases) and the clinical pathological features were evaluated.

Compared with the other groups, the IgG4-CP group was more common in men and associated with low-grade fever and massive pericardial effusion with frequent recurrence. Deaths resulting from heart failure occurred in a few cases of the IgG4-CP group, but not in other groups. An increase in C-reactive protein and a high positivity rate of anti-nuclear antibodies frequently occurred in the IgG4-CP group. Histologically, the IgG4-CP group included lymphoid follicle, eosinophil infiltration and few calcifications.

Pericardial IgG4-RD occurs not only as nodular lesions, but also as thick-walled CP, and accounts for approximately 40% of thick-walled CP cases of unknown cause. The predominant clinical characteristic was refractory and recurrent pericardial effusion. Recognising IgG4-RD as a cause of CP is important to initiate appropriate therapy.