Gout presenting as a popliteal cyst. A case of pseudothrombophlebitis.

A 64-year-old man with progressive swelling and erythema of his right calf preceded by dull aching in the right popliteal fossa was presumed to have deep vein thrombophlebitis. A venogram revealed normal circulation in the right lower leg, and an ultrasound examination of the right popliteal fossa revealed a 2 X 5-cm popliteal cyst. Fluid aspirated from the cyst confirmed the diagnosis of gout. Popliteal cysts associated with gout are rare, and those that rupture, leak, dissect, or enlarge can mimic thrombophlebitis (a phenomenon known as pseudothrombophlebitis). Thus, the primary care physician should consider the diagnosis of popliteal cyst in patients who appear to have deep vein thrombophlebitis.