We report the case of a 36-year-old woman with a recent upper respiratory illness who presented with chest pressure, lasting for five days, which improved with leaning forward. Physical examination and laboratory studies were unremarkable. Chest computed tomography scan revealed a 6.9 cm × 4 cm × 2.5 cm pericardial cyst. The patient was diagnosed with pleuropericarditis complicated by a pericardial cyst. Pericardial cysts are rare mediastinal lesions that are often congenital, but may be inflammatory. If symptomatic, surgical resection or percutaneous aspiration may be considered. In our patient, treatment with ibuprofen and colchicine resulted in a decrease in cyst size, suggesting an inflammatory component. We describe an uncommon case of reduction of a pericardial cyst shortly after treatment of pericarditis due to a probable viral infection. Non-operative management of pericardial cysts may be appropriate in these select cases. <Learning objective: Pericardial cysts are rare, congenital, mediastinal lesions. Patients are often asymptomatic or may present with atypical chest pain, cough, or compressive symptoms. In previously reported cases, patients with pericardial cysts had undergone surgical intervention. Pericardial cysts may have an inflammatory component, and can be complicated by infections. Thus, non-operative management may be more appropriate in certain situations.>.