Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Aneurysmal dilation of the aortic arch and descending thoracic aorta appears similar to the prior chest radiograph of ___ . The lungs are clear without focal opacity , pulmonary edema , pleural effusion or pneumothorax . Moderate cardiomegaly is stable .
    OUTPUT:
    
Stable widening of mediastinum due to known aneurysmal dilation of the aortic arch and descending thoracic aorta .