IgG4-related disease manifesting as pericarditis with elevated adenosine deaminase and IL-10 levels in pericardial fluid.

A 78-year-old female with massive pericardial effusion fulfilled diagnostic criteria for immunoglobulin G4 (IgG4)-related disease. Although her adenosine deaminase (ADA) level in the pericardial effusion was high, all the tests for tuberculosis infection were negative. Immunostaining of the pericardium biopsy specimen revealed remarkably increased IgG4-positive cells. This is the first report describing IgG4-related pericarditis with elevated ADA level. We also demonstrate the elevated interleukin-10 (IL-10) level in pericardial fluid and IL-10-producing T-cells in the pericardium.