Sonic silhouetting of the aorta.

The diagnosis of diseases involving and arising from structures around the abdominal aorta has been described. Sonic silhouetting of the wall of the aortic due to lymphomatous involvement of the para-aortic lymph nodes is well known. It may be found with metastatic para-aortic lymphadenopathy, retroperitoneal fibrosis and pancreatic carcinoma where the tumor is adjacent to the aortic wall. Sonic silhouetting of the aorta associated with a pancreatic mass indicates malignancy. Extensive sonic silhouetting due to pancreatic carcinoma can have the appearance of a clot containing abdominal aortic aneurysm.