Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . The mediastinal and hilar contours are normal . The pulmonary vasculature is normal . Lungs are clear except for a small linear opacity in the left lower lung at the level of the fifth anterior rib . No pleural effusion or pneumothorax is seen . There are no acute osseous abnormalities .
    OUTPUT:
    
Linear opacity in left lower lung favors atelectasis , but an early focus of pneumonia is also possible in this immunosuppressed patient . Short - term followup radiographs may be helpful in this regard .