["Pseudothrombosis" of the lower leg, induced by a ruptured Baker's cyst].

A sudden onset of unilateral swelling and tenderness on pressure of the calf with no history of trauma is suggestive of vein thrombosis. Baker cysts, especially if ruptured, mimic the clinical picture of deep vein leg thrombosis. The examination method of choice is duplex sonography. We report on a 30-year-old man who was admitted to our hospital with signs of deep vein leg thrombosis. Phlebography revealed normal venous circulation. Examination by duplex sonography showed a ruptured Baker cyst. No intra-articular lesions of the knee joint were revealed by arthroscopy. Histological examination of the biopsy specimens of the synovia showed no specific pathologic condition. The clinical signs improved with conservative treatment.