Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The background density of the lung parenchyma is increased compared to prior particularly in the left hilar and suprahilar region . This corresponds with bronchiolar nodularity evident on the concurrent chest CT , raising the concern for a viral or atypical infection such as ___ . There is no confluent consolidation or pneumothorax . There is no vascular congestion or pleural effusions . Cardiomediastinal and hilar contours are within normal limits .
    OUTPUT:
    
Left hilar and suprahilar density better characterized on concurrent chest CT , concerning for a viral or atypical infection ( ___ ) .