[Recurrent pigmented villonodular synovitis (PVNS)].

Aim: The pigmented vilionodular synovitis (PVNS) is a tumour like disease of unknown origin that often shows recurrence. The pathogenesis is still unknown and therefore the question of the right therapy is not resolved.
Material: With a case report of a patient with recurrence after two arthroscopic synovectomies, PVNS is discussed against the background of the clinical, histological, and radiological features.
Results: We performed an open synovectomy and cystic lesions in both condyles of the femur and proximal tibia were filled with homologous and autologous cancellous bone. Three months later the patient had no pain and the bone density in the former cystic lesions was appropriate.
Discussion: The pathogenesis is still unknown. Diagnosis often is obtained much too late due to missing specific symptoms. PVNS occurs in local forms as well as in a diffuse growth pattern. Recurrence rates of up to 78% are very high. Besides arthroscopic and open synovectomy, the treatment with radiosynoviorthesis must be considered. Depending on the growth pattern, the tumour masses, and the affected joint, the therapy has to be chosen very carefully and sometimes different forms have to be combined if a recurrence--free result is to be achieved.