Rapid recurrence of a giant popliteal cyst in a patient with rheumatoid arthritis.

Despite increasing knowledge of etiopathogenesis, therapy, and recurrence rate of popliteal cysts, they nevertheless occasionally represent clinical problems. We report the case of a 58-year-old rheumatoid arthritis patient in whom a giant recurrent cyst developed very shortly after primary excision. Reports of such large popliteal cysts are rare and very few cases were reported in rheumatoid arthritis patients. Moreover, no such giant recurrent cysts formed so shortly after primary excision. Thus, its occurrence may be partially ascribed to the specific dynamics of fluid flows caused by the absence of a valve-like mechanism. With regard to treatment, it appears that synovectomy may reduce the production of synovial fluid, but reinforcement of the thin tissue with capsuloplasty may also be important. Immobilization is necessary so that initiation of the healing process is not disturbed.