Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Blunting of the left costophrenic angle and subtle retrocardiac opacity are noted , potentially atelectasis . The lungs are otherwise clear . The cardiomediastinal silhouette is stable . No focal osseous abnormalities identified pain .
    OUTPUT:
    
Retrocardiac and left costophrenic angle opacity potentially atelectasis , infection not excluded .