Multifocal PVNS in a child--followed over 25 years.

Pigmented villonodular synovitis (PVNS) is a rare disorder of unknown aetiology, characterised by a destructive fibrohistiocytic proliferation with production of villous and nodular protrusions. The disease is commonly monoarticular, and involves the knee in 80% of cases. Occurrence in a child and involvement of multiple joints are extremely unusual. We present a case of multiple joint PVNS in a patient who first presented at the age of five and was subsequently followed up for over twenty-five years. The literature on the subject is briefly reviewed.