Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low . Worsening opacity in the posterior basilar segment of the left lower lobe . The heart is top - normal in size . Mediastinal contours and hila are normal . No pleural effusion .
    OUTPUT:
    
Worsening opacity in the posterior basilar segment of the left lower lobe concerning for developing infectious pneumonia .