The pseudothrombophlebitis syndrome.

Sixty-two patients with popliteal or calf synovial cysts defined by arthrography are presented, of whom 34 had the pseudothrombophlebitis (PTP) syndrome. While the clinical manifestations of PTP may closely mimic thrombophlebitis, including the presence of calf pain, swelling and warmth, and a positive Homans' sign, the helpful descriminating features include the presence of inflammatory joint disease (91%), concomitant pain and swelling of the knee (94%), a demonstrable knee effusion (91%) and the absence of deep venous tenderness or cord. Except for seven patients with large intact Baker's cysts, the PTP syndrome was associated with synovial cyst dissection (18 patients), rupture (5 patients), or both (4 patients). Of those with arthrographically demonstrated Baker's cysts, only 27 (44%) had a palpable mass in the popliteal fossa and another 4 (12%) a mass in the calf. Popliteal fossa pain was noted in 22 (35%). Thus, clinical features are far less sensitive than arthrography in the diagnoses of both synovial cysts and pseudothrombophlebitis. Among patients with rheumatoid arthritis there were no differences in the severity or duration of disease or the extra-articular features in patients with and without synovial custs or the PTP syndrome. The therapeutic implications of pseudothrombophlebitis are of major significance with respect to the avoidance of anti-coagulation and the prompt response to intra-articular corticosteroids. Possible mechanisms of synovial cyst formation and unusual presentations of synovial cysts are discussed, and the literature is reviewed.