A ruptured syphilitic descending thoracic aortic aneurysm. The characteristic findings on computed tomography for the etiological diagnosis of aneurysm.

We report the case of a 72-year-old man with a ruptured syphilitic descending thoracic aneurysm who underwent an emergency operation and successful graft replacement. Preoperative physical examination showed a pulsative mass on the left back. Preoperative computed tomography showed bone destruction in the TH6 to TH10 thoracic vertebrae and ribs and penetration (or rupture) of the aneurysm into the subcutaneous tissue. During the period of preoperative evaluations, free wall rupture of the aneurysm occurred and emergency operation for graft replacement was performed. The microscopical examination of the aneurysmal wall revealed the syphilitic changes. In literature, the vertebral destruction by atherosclerotic aneurysm is usually located at the TH12 to L3 of vertebral bodies. From the findings of this patient and a study of existing literature, we concluded that the finding of vertebral bone beyond TH12 to L3 region on CT examination of the aneurysm could be a etiological characteristic finding for syphilitic aortic aneurysm.