Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A pigtail drainage catheter has been placed into the left lower hemithorax since the prior examination with marked reduction in a loculated left - sided pleural effusion . However , there is considerable persistent opacification along the pleural surfaces of the left mid to lower lung as well asretrocardiac opacification . Associated with the presence of the catheter , there is now a small amount of air associated with the collection . Moderate interstitial abnormality appears increased in severity .
    OUTPUT:
    
Status post placement of pleural drain on the left with substantial decrease in loculated pleural effusion . Increasing interstitial abnormality for which differential considerations include interstitial pulmonary edema or perhaps less likely atypical pneumonia .