Retroperitoneal false aneurysm presenting as anterior thigh pain and weakness: a case report.

This case highlights the importance of considering retroperitoneal pathology in the differential diagnosis of anterior thigh pain and weakness. We describe a woman in her mid seventies with a history of a left total hip arthroplasty and lumbar decompression who presented with left anterior thigh pain and left lower-extremity weakness. A computed tomography scan of the retroperitoneum revealed a mass along the left iliopsoas muscle. An arteriogram revealed a large false aneurysm that communicated with the left common femoral artery. Surgery to resect the aneurysm revealed exposed parts of the hip replacement that may have contributed to the formation of the aneurysm. We concluded that imaging of the retroperitoneum should be considered in any patient presenting with anterior thigh pain and weakness.