IgG4-Related Pericarditis

BACKGROUND: IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory condition that rarely affects the pericardium. When present, it may manifest as recurrent or constrictive pericarditis, posing diagnostic and therapeutic challenges. CASE SUMMARY: We present 5 patients with biopsy-proven IgG4-RD involving the pericardium (IgG4-RD pericarditis) who developed constrictive physiology. All patients initially received medical therapy, including nonsteroidal anti-inflammatory drugs, colchicine, corticosteroids, and, in some cases, biologics. Despite these interventions, persistent or progressive symptoms necessitated surgical pericardiectomy. Histopathology consistently revealed dense lymphoplasmacytic infiltrates with >40% IgG4-positive plasma cells. Following surgery, all patients demonstrated symptomatic improvement. Two patients required ongoing immunosuppression, whereas the remainder remained stable without recurrence of constriction. DISCUSSION: IgG4-RD pericarditis should be considered in cases of recurrent or refractory pericardial disease. Diagnosis requires integration of multimodality imaging, invasive hemodynamics, and histopathology. Although medical therapy may provide partial benefit, pericardiectomy remains definitive in cases of established constriction. Long-term multidisciplinary follow-up is essential given the risk of multisystem involvement and relapses. TAKE-HOME MESSAGES: IgG4-RD pericarditis is a rare but important cause of constrictive physiology. Multimodality imaging and pericardial biopsy are critical for diagnosis. Surgical pericardiectomy is often curative, but lifelong follow-up is necessary to monitor systemic disease.