Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are clear . There is no focal consolidation or pneumothorax . There is no vascular congestion or pleural effusions . Lateral view demonstrates an enlarged posterior cardiac margin . Differential includes left atrial enlargement , subcarinal bronchogenic cyst or possible adenopathy if the patient has a known extrathoracic malignancy . The cardiac silhouette is moderately enlarged .
    OUTPUT:
    
1 . Moderately enlarged posterior cardiac margin of uncertain etiology . Likely atrial enlargement or possibly a bronchogenic cyst , though adenopathy is within the differential if there is known extrathoracic malignancy . Comparison with prior images would be helpful to further characterize . 2 . Moderate cardiomegaly