Pigmented villonodular synovitis of the knee in skeletally immature patients

INTRODUCTION: Pigmented villonodular synovitis (PVNS) is a benign idiopathic proliferative disorder that results in villous or nodular formation in the joints, tendons sheaths, and bursae. As PVNS is a rare pathology in children, diagnosis is often delayed. In this study, we analyze the therapeutic methods used and results obtained in the treatment of this pathology. MATERIALS AND METHODS: All patients with PVNS of the knee seen between January 1988 and June 2006 were evaluated. We assessed the form of presentation, time to diagnosis, previous diagnosis, type of treatment, relapse, and the need for subsequent treatment. RESULTS: Nine patients with age range 2-15 years and a mean follow-up of 8.5 years were evaluated. Four patients had the diffuse form and four had the localized or nodular form; all of them were intra-articular. In only three cases were preoperative radiographic findings observed. The mean delay in diagnosis was 18 months. Open resection was performed in five patients and arthroscopic resection in four. Joint function was satisfactory in 78% of the patients at the last follow-up and there were no postoperative recurrences. CONCLUSIONS: Magnetic resonance imaging (MRI) is a useful diagnostic tool and the way to detect relapse, and allows accurate determination of the tumor extent. Surgery is the treatment of choice. Worse results are directly related to delay in diagnosis.