Case Presentation: A 17-year-old female presented with a one-month history of persistent dry cough, worsened by lying flat, requiring multiple pillows to sleep comfortably. Initially treated for presumed pharyngitis, her symptoms persisted, prompting further evaluation. Echocardiography revealed a large pericardial effusion with a normal ejection fraction, leading to hospital admission. Imaging studies identified a 3.5 [...]