A case report of cystic adventitial degeneration communicating with the hip joint in the external iliac artery

: Cystic adventitial degeneration is an uncommon cause of arterial obstruction. Its etiology is debated. We report a case in which the left external artery was affected and the cystic mass communicated with the hip joint. The findings of this case support the embryonic theory that the articular synovium and adventitial cysts have the same mesenchymal origin.