Presenting With Pericardial Tamponade.

(MP) is a common cause of community acquired pneumonia in school aged children but rarely causes pericardial and pleural effusions in a previously healthy host. We report an adolescent presenting with pericardial effusion with tamponade and pleural effusions most likely caused by MP infection. Definitive diagnosis of pericardial effusion is a challenge even when pericardial fluid or tissue is available. Serology is the mainstay of diagnosis. IgM is a reliable indicator of recent MP infection, but rising titers are needed which could delay diagnosis. Pericardial effusion with tamponade is a rare presentation of MP infection. As appropriate treatment significantly affects the outcome, investigating for MP should be part of the routine workup for pericarditis of unknown etiology.