Nondilated abdominal aortic rupture caused by acute type B aortic dissection.

A 31-year-old man presented with sudden abdominal pain. Computed tomography showed type B aortic dissection and a huge retroperitoneal hematoma. Accordingly, we diagnosed rupture of the abdominal aorta which was of almost normal caliber. Emergency open abdominal aortic repair was performed successfully. Pathology of the aortic wall revealed diffuse medial degeneration with severe elastin fragmentation, but gene analysis found no gene mutation that could lead to a connective tissue disorder.