Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single portable chest radiograph demonstrates hyperexpansion of lungs with relative lucency of the upper lung zones , consistent with chronic lung disease . There is a persistent asymmetric increased opacity in the right lung base , similar across multiple prior studies and possibly representing combination of scarring and atelectasis . No new focal opacifications evident . No pleural effusion or pneumothorax identified . Mediastinal and hilar contours are unremarkable . Heart size is top normal . Stable positioning of dual - chamber pacemaker noted . No osseous abnormality is present .
    OUTPUT:
    
No acute intrathoracic process . Stable linear right lower lung opacifications , unchanged across multiple prior studies on background of chronic lung disease .