Ruptured isolated external iliac artery true aneurysm associated with cystic medial necrosis: report of a case.

We report a case of a ruptured isolated true external iliac artery aneurysm (EIAA). A 78-year-old woman was admitted to our institution in a shock state after the sudden onset of severe pain in the right hypogastric region. A pulsating mass was found in her right lower abdomen. Computed tomography (CT) with contrast medium showed an isolated EIAA, 40 mm in diameter, with a massive retroperitoneal hematoma. She underwent emergency resection of the aneurysm and reconstruction of the affected artery, without any complications. Histological examination confirmed a true aneurysm caused by cystic medial necrosis (CMN). She had no ocular, cardiac, or orthopedic abnormalities. We review the literature on isolated true aneurysms of the external iliac artery, which are extremely rare, and discuss their clinical manifestations.