Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is within normal limits . Opacity within the retrosternal region on the lateral view corresponds to known anterior mediastinal mass , better assessed on the previous PET - CT . Mediastinal and hilar contours are otherwise unchanged . Pulmonary vasculature is not engorged . Patchy opacities are noted within both upper lobes and left lung base , nonspecific , but infection is not excluded . No pleural effusion or pneumothorax is seen . No acute osseous abnormalities demonstrated .
    OUTPUT:
    
Known anterior mediastinal mass is better appreciated on the previous PET - CT . Patchy opacities in both upper lobes and left lung base are nonspecific but may reflect areas of infection .