Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a large opacity in the left upper lobe , which is new since the prior study compatible with pneumonia as well as atelectasis . Left lower lobe as well as the entire right lung appear clear . No pleural effusion is noted . Cardiac size remains stable . The aorta is slightly tortuous . The bones are intact , although evaluation of the upper thoracic spine is limited . There is no abdominal free air .
    OUTPUT:
    
Left upper lobe opacity concerning for pneumonia .