Pericarditis as a manifestation of IgG4-related disease.

IgG4-related disease (IgG4-RD) is a systemic, immune-mediated fibro-inflammatory disease that can affect virtually every organ system. It is usually insidious in onset and often mimics malignant or other inflammatory disorders. Diagnosis frequently requires a combination of clinical, serological, radiographic, and histopathological features, including increased serum-IgG4 levels and tissue infiltration of IgG4-positive plasma cells with associated fibrosis. Unlike more frequently affected sites, including the hepatobiliary system, salivary glands and retroperitoneum, pericardial involvement of IgG4-RD has only rarely been described. We report the case of a 76-year-old woman presenting with refractory pericarditis and imminent cardiac tamponade, successfully treated with therapeutic pericardiectomy. A diagnosis of IgG4-RD was made based on elevated serum-IgG4 levels and the presence of typical pericardial histopathological findings, meeting all 3 of the 2011 comprehensive diagnostic criteria for IgG4-RD. Following pericardiectomy, the patient remained in remission without a need for glucocorticoids or additional immunosuppressive therapy. Adding to this case, we reviewed the literature for previously described cases of IgG4-RD presenting with pericarditis and described their characteristics and the available treatment options. Our case-based literature review provides a clear overview of the diagnostic process for IgG4-RD and the need to apply classification criteria with the necessary caution, particularly in the case of rare disease manifestations, including pericarditis.