Since<unk> s are often asymptomatic, the most common diagnosis is through incidental finding on a chest x-ray. When patients have symptoms, transthoracic echocardiogram is one of the first tests used to look for a<unk> . CT or MRI may also be used to diagnose<unk> s. On CT and MRI a<unk>  will commonly appear as a round, fluid-filled structure surrounded by thin walls. Diagnosis of a<unk>  can also be made before birth using ultrasound. The differential diagnosis for a suspected<unk>  includes a bronchial<unk> ,<unk>  effusion, teratoma, lymphangioma,<unk>  fat, congenital diaphragmatic hernia, neuroenteric<unk> , and congenital<unk>  from the primitive foregut. A<unk>  also may look similar on imaging to a<unk>  diverticula, which is connected to the pericardium and not fully walled off like a<unk> .
Pericardial cyst
Cardiac myxoma
Annuloaortic ectasia
Crisscross heart
Overriding aorta
Cardiac fibroma
Pulmonary artery sling
Aortoesophageal fistula