Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest demonstrate an ill - defined opacity within the posterior left lower lobe , compatible with pneumonia in the appropriate clinical setting . The lungs are otherwise well expanded with no evidence of pulmonary edema , pleural effusion or pneumothorax . The aorta is tortuous , and unchanged . Additionally , a small hiatal hernia is re - demonstrated . The heart size is stable . Multiple healed left - sided rib fractures are again identified .
    OUTPUT:
    
Ill - defined opacity in the posterior left lower lobe , could represent pneumonia in the appropriate clinical setting .