Hereditary multiple exostoses with pseudoaneurysm.

A 16-year-old male patient with hereditary multiple exostoses (HME) was found to have a pseudoaneurysm of the left popliteal artery caused by osteochondroma in the lower femur. The diagnosis was confirmed by ultrasound, magnetic resonance imaging and magnetic resonance angiography without the need to perform an angiogram. The osteochondroma was excised and the popliteal artery was repaired with a saphenous graft. Vascular complications are extremely rare in HME, pseudoaneurysm being the most common and mostly located in the popliteal artery. This complication should be considered in young HME patients with a mass at the knee region. The radiological spectrum of investigations allows the diagnosis of this complication with proper and less invasive management procedures for the patient.