Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac , mediastinal , and hilar contours appear unchanged . There is no pleural effusion or pneumothorax . A known nodule , which has been stable , projects over the right upper lobe and course of the right second rib , not significantly changed . Otherwise , the lungs appear clear .
    OUTPUT:
    
Stable lung nodule in the right upper lobe . No evidence of acute disease .