Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Mediastinal and hilar contours are unremarkable . Increased interstitial markings are demonstrated the lung bases , moreso than on the prior exam , with more focal opacity within the left lower lobe . No pleural effusion or pneumothorax is present . There is scarring within the lung apices . No acute osseous abnormalities detected .
    OUTPUT:
    
Increased interstitial markings within the lung bases with more focal opacity in the left lower lobe . Findings may reflect pneumonia with mild pulmonary vascular congestion , but atypical infection should also be considered .