Painful swelling of the calf is a common clinical problem. Distinguishing deep venous thrombosis from pseudothrombophlebitis can be difficult Pseudothrombophlebitis syndrome has been associated with ruptured/dissecting popliteal synovial cysts, localized myositis, inflammatory pseudotumor, popliteal artery aneurysm, and ruptured gastrocnemius, popliteal and/or plantaris tendon/muscles. In this report, we describe two patients for whom magnetic resonance imaging rapidly and accurately identified the cause of pseudothrombophlebitis, thus helping to avoid further testing and unnecessary anticoagulation.