Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP upright and lateral views the chest provided . There is subtle elevation of the left hemidiaphragm unchanged with persistent retrocardiac and left lower lobe opacity which is mostly linear in appearance likely reflecting atelectasis or scarring though difficult to exclude a subtle pneumonia at this location . Right lung is clear . No large effusion or pneumothorax . Heart size is normal . Mediastinal contours unremarkable . Imaged bony structures are intact . No free air below the right hemidiaphragm .
    OUTPUT:
    
Possible left lower lobe pneumonia in the appropriate clinical setting .