[MEP-22] Acute Cardiac Tamponade Secondary to Pericardial Cyst.

Pericardial cysts are rare, with an estimated incidence of approximately 1 in 100,000, and are typically benign and incidentally discovered. However, pericardial cysts leading to cardiac tamponade are exceptionally rare. Herein, we presented the case of a five-year-old male patient who was admitted to the emergency department with symptoms of acute shortness of breath. Initial echocardiography revealed signs of cardiac tamponade, along with the presence of a cystic lesion within the pericardial cavity. Subsequent computed tomography and magnetic resonance imaging confirmed the presence of the cyst, leading to an emergency surgical intervention. A median sternotomy was performed, revealing a significant accumulation of hemorrhagic liquid, which was aspirated and sent to the pathological examination. A large cyst was identified situated between the aorta, superior vena cava, and right pulmonary artery. The cyst was excised and sent for pathological examination. The procedure was completed without complications. Histopathological analysis of the cyst revealed no evidence of malignancy. The patient had an uneventful recovery and was discharged on the sixth postoperative day in good condition. The patient continued to do well at the 10-month follow-up. This case underscores the importance of considering pericardial cysts in the differential diagnosis of cardiac tamponade, despite their rarity. Early imaging and surgical intervention are critical to preventing fatal outcomes in such cases.