Pigmented Villonodular Synovitis of the Knee Joint: A Case Report

A 23-year-old girl presented with an insidious gradually progressing swelling over the right knee for one year with occasional pain. There was no history of any injury and laboratory studies were normal. On fine needle aspiration cytology, a probable diagnosis of pigmented villonodular synovitis was made, confirmed on biopsy. The lesion was excised and the patient has not had a recurrence in one year. This case report emphasises that the diagnoses of pigmented villonodular synovitis should be considered in any case of chronic joint effusion.