Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unremarkable . Pulmonary vasculature is normal . Mild increased interstitial markings are demonstrated within the lung bases , and likely reflect a mild chronic interstitial abnormality , as suggested on the prior CT abdomen . Additionally , patchy opacity within the left lung base is concerning for an area of developing infection . No pleural effusion or pneumothorax is present . No acute osseous abnormality is detected .
    OUTPUT:
    
Patchy opacity in the left lung base concerning for pneumonia . RECOMMENDATION ( S ) : Follow up radiographs after treatment are recommended to ensure resolution of this finding .