Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Again seen are ___ midline median sternotomy suture wires and multiple mediastinal surgical clips . The thoracic aorta is mildly tortuous , similar to prior . Otherwise , the cardiomediastinal silhouette is unchanged , and within normal limits . The bilateral hila are unremarkable . New since prior is the development of retrocardiac opacification and silhouetting of the medial left hemidiaphragm . Lateral view demonstrates posterior lower lung opacification . Findings overall are compatible with consolidation involving the left lower lobe . The remainder of the left lung is clear . The right lung is clear . There is no evidence of pulmonary vascular congestion . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Retrocardiac opacity compatible with left lower lobe pneumonia .