Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest radiographs demonstrate clear lungs bilaterally . Heart size is top normal . Hilar contours are within normal limits . Within the anterior mediastinum there is an abnormal contour previously present on study dated ___ and unchanged , potentially representative of the pulmonary outflow track or soft tissue within the prevascular mediastinal space . There is no evidence of pulmonary edema . There is no large pleural effusion . No pneumothorax . Imaged osseous structures and upper abdomen are unremarkable .
    OUTPUT:
    
No acute intrathoracic abnormality . Unchanged appearance of anterior mediastinal contour which may be representative of the pulmonary outflow tract or alternatively adjacent soft tissue within the prevascular space . If available , radiographs prior to ___ should be reviewed . If clinically warranted , dedicated imaging with chest CT can be performed for further investigation .