Rare complication of saccular aneurysm and histological dissection: an autopsy study of 5865 elderly cases

The purpose of this study was to examine complicated lesions of saccular aneurysm and dissection. We investigated the ascending aortae in 5865 consecutive elderly autopsy cases, and 5 cases (0.085%) of aortic saccular aneurysms associated with dissection at the edges were selected. Their edges characteristically protruded like a shelf, which histologically consisted of an inner part of the dissected media. All patients were female and their mean age was 76.8 (67-89) years. The aneurysmal walls at the center showed severe fragmentation and disappearance of the elastic lamellae of the remaining outer media. Thus, partial sections of these lesions were not sufficient but cross-sections of the whole diseased regions including the edges were essential for diagnosis. One patient had 3 saccular aneurysms and an adjacent shallow depression, which we called "healed microscopic dissection". Histologically, it showed disappearance of the inner media and was replaced by fibrosis in continuation from the intima. This lesion showed no findings of intramural hemorrhage or thrombus, and thus it will differ from organized thrombi in the dissected false lumen. Another patient presented had an aneurysmal rupture which resulted in cardiac tamponade. This case implies the need for surgical treatment of this entity.