Adventitial cystic disease of the popliteal artery.

In a 27-year-old man with claudication, computed tomography (CT) demonstrated a popliteal cyst and an adventitial cyst of the popliteal artery. Adventitial cystic disease was unexpected because the patient had a diminished pedal pulse on plantar flexion of the foot, a physical finding suggesting popliteal artery entrapment syndrome. CT was useful in the initial examination of this young patient with suspected popliteal vascular disease because of its accuracy and noninvasiveness.