Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There are ill - defined bibasilar patchy opacities , which have progressed compared to the prior radiograph , and may represent atelectasis , however an underlying pneumonia can not be excluded . The previously visualized nodule is not definitively seen on this examination . The pulmonary vasculature is normal . The cardiomediastinal silhouette is stable . There is no pleural effusion . There is no pneumothorax .
    OUTPUT:
    
Ill - defined bibasilar opacities , which are obscuring the previously visualized nodule , and may represent atelectasis or in underlying pneumonia .