“…2,5,8,15) Spontaneous STA aneurysms, in contrast, tend to be associated with arteriosclerosis, are characterized by atherosclerotic plaques and calcification, and most are identified as true aneurysms by histological examination. 1,6,11,14) Although we first thought that the STA aneurysms in our elderly patients were attributable to arteriosclerosis, we identified them as pseudoaneurysms based on the histological examination of the aneurysm wall revealing disruption of the internal elastic lamina and presence of the connective tissue and adventitia only. 16) Spontaneous STA pseudoaneurysms in the absence of trauma are extremely rare, with only one previously reported case.…”