Popliteal cysts: presentation as thrombophlebitis.

Synovial-lined cysts in the popliteal space associated with rheumatoid arthritis or meniscal tears may compress the popliteal vein and produce signs and symptoms suggestive of thrombophlebitis. Because of a presumptive diagnosis of thrombophlebitis, venography may be performed initially and demonstrate compression of the popliteal vein by an extrinsic mass. The correct diagnosis of a popliteal cyst can easily be made with B-mode ultrasonography, and, if desired, confirmed by arthrography. Four cases are presented which emphasize these features.