Dissecting aneurysm: a clinicopathologic and histopathologic study of 111 autopsied cases.

One hundred eleven autopsy cases of dissecting aneurysm were collected from western Japan. The ratio of males to females was 3:2 and the sixth and seventh decades of life were most frequently affected. All 11 cases of Marfan's syndrome were in patients under 40 years of age. DeBakey's type III dissections showed a male predilection and more severe atherosclerosis than in control cases. Many patients with types I and II dissections died of hemorrhage in the acute phase, while many patients with type III dissection died in the subacute or chronic phase, and half of the patients died of diseases other than hemorrhage. Hypertension was recognized in 73.7% of the 95 cases which showed no other obvious risk factors. Histologic examinations suggested that cystic medial necrosis was related to the pathogenesis of the disease in Marfan's syndrome, but was not so apparent in non-Marfan's syndrome. Laminar medial necrosis was found in many cases, but was considered to be a secondary ischemic change following dissection, as supported by other investigators. There were only a few cases in which dissection seemed to be directly caused by atherosclerosis.