Primary malignant fibrous histiocytoma of the aorta associated with aortic dissection. We report a unique case of primary aortic malignant fibrous histiocytoma presenting clinically as aortic dissection. To our knowledge, this occurrence is the first ever reported. The magnetic resonance imaging technique may provide superiority in the differential diagnosis between tumor and hematoma of aortic dissection. Aortic tumor, although rare, should be included among the causes of aortic dissection. 