[A swollen leg disclosing a popliteal cyst. Apropos of a misleading case].

A patient was admitted with a clinical suspicion of left sural thrombophlebitis. Analysis of the clinical features and the results of rheoplethysmography, phlebography, arteriography and, most importantly, ultrasonography led to the diagnosis of popliteal synovial cyst and demonstrated the vascular repercussions of this lesions responsible for the swollen leg. A review of the literature confirms the frequently misleading clinical features of popliteal cysts. The authors present a strategy for the investigation of these cases, based on vascular functional investigations and in particular ultrasonography.