Pseudoaneurysm of the popliteal artery caused by exostosis of the femur: case report and review of the literature.

A 13-year-old boy with a solitary exostosis of the left femur was seen with a pseudo-aneurysm of the popliteal artery. When left leg pain occurred 3 months earlier, radiographic examination revealed an exostosis with a cartilage cap. Serial radiographic examination demonstrated gradual disruption of the cartilage cap of the exostosis as the pseudoaneurysm developed. An exostosis with an irregular surface was found at surgery. A literature review disclosed 39 similar cases in which loss of the cartilage cap was considered as one of the causes of the aneurysm formation. Considering the clinical course of our patient, however, we believe that exostoses lose their cartilage caps by pressure destruction due to the aneurysms. It is highly probable that loss of the cartilage does not cause the aneurysms.