[A differential diagnosis of sural phlebitis: popliteal cysts. Value of ultrasonography (author's transl)].

Two cases are reported of popliteal cysts simulating sural phlebitis, one in a patient with lupus, the other during the course of rheumatoid arthritis. Diagnosis is based upon the following signs: sudden onset of pain, sometimes after effort, and in the knee rather than in the calf, and more especially ecchymosis occurring in the internal supramalleolar region. The decision as to whether anticoagulant treatment should be instituted must be based on the certitude of the diagnosis, and this can be obtained in an atraumatic manner by ultrasonography of the popliteal fossa as shown by iconography.