Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single AP upright image of the chest was obtained . There is a left basilar opacity . No right sided pleural effusion . No pulmonary edema . Unchanged markedly dilated cardiac silhouette . No pneumothorax . No bony abnormality . No free air below the hemidiaphragm .
    OUTPUT:
    
Left basilar opacity possibly due to pneumonia , effusion , atelectasis or a combination of the above . Stable severe cardiomegaly .