Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A 6 .0 x 5 .6 cm left perihilar mass is identified and compatible with known malignancy . This mass has not significantly changed in size compared with prior chest radiograph . No other focal opacities are noted . Cardiomediastinal and hilar contours are unremarkable . There is no pleural effusion or pneumothorax . Minimal atelectasis is noted in the lung bases , but no focal consolidation . No rib fractures are identified .
    OUTPUT:
    
Unchanged rounded perihilar mass compatible with known malignancy . Mild bibasilar atelectasis .