Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since the prior chest x-ray of ___ , a left effusion has developed . Some volume loss is present , but some of the opacification could be due to left lower lobe pneumonia . Clinical correlation would be necessary . There is no evidence of failure . The right costophrenic angle is sharp .
    OUTPUT:
    
New onset of left effusion . Underlying pneumonia could be present .