Pericardial rupture of mediastinal mature cystic teratoma: An unusual cause of pediatric acute chest pain.

A previously healthy 12-year-old girl presented to the emergency department with severe chest pain and dyspnea that woke her from sleep. She had short-term syncope just before the emergency admission. On physical examination, respiratory rate was 26 breaths per minute while resting, and blood pressure was 92/56 mmHg. Other physical examination findings were insignificant. She had no past medical history, and her family history was unremarkable. Laboratory test results showed elevated C-reactive protein (27 mg/L; reference range: <5 mg/L) and white blood cell count (13.7 K/μL; reference range: 4-12 K/μL). Other laboratory test results were within normal limits, including troponin T value (3 ng/L; reference range: 3-14 ng/L). An electrocardiogram showed 1 mm ST-segment elevation in bipolar (D1 and D2) limb leads, and augmented vector foot leads, and echocardiography revealed a complicated pericardial effusion and a suspicious mass adjacent to the left ventricle.