Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There is a pole 4 .5 cm solid retrocardiac mass . Is unclear if this is in the lung given that we only on a single view . There is a small left effusion . There is a central venous catheter with tip in the right atrium .
    OUTPUT:
    
___ .5 cm retrocardiac opacity could represent a lung mass . CT would be helpful for further evaluation if clinically indicated .