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 . Obscuration of the left heart border by left upper lobe atelectasis is chronic . Lateral view shows a small region of atelectasis or pneumonia in the right middle lobe . No pleural effusion or pneumothorax is seen .
    OUTPUT:
    
Right middle lobe pneumonia or atelectasis .