Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A vague opacity in the left upper lung is slightly more prominent than in ___ and not well visualized on lateral view . The lungs are otherwise well expanded and clear . Mediastinal contours , hila , and cardiac silhouette is normal . No pleural effusion , pulmonary edema , or pneumothorax .
    OUTPUT:
    
Increased prominence and left upper lobe opacity could suggest the possibility of pneumonia in the right clinical setting .