Spontaneous rupture of aortic arch through an atheromatous plaque resulting in pseudoaneurysm

An autopsy case of spontaneous rupture of aortic arch through an atheromatous plaque which resulted in pseudoaneurysm is reported. The aorta was involved by severe atherosclerosis with scattered calcifications over the entire surface, and there was a fusiform aneurysm protruding from a transmural tear in the aortic arch. Histopathologically, no evidence of dissection or inflammatory change was noted in the aorta, and no histologic component of the aortic media was observed in the aneurysmal wall. However, degenerative change of cystic and laminar medial necrosis were recognized near the ruptured site. Such localized degenerative change was considered to be caused by circulatory disturbance which originated from disruption of the vasa vasorum due to aortic rupture.