[Pigmented villonodular synovitis with polyarticular presentation]. / Sinovitis villonodular pigmentada de presentación poliarticular.

Pigmented villonodular synovitis (PSV) rarely involves more than one joint, and its occurrence in children is uncommon. One case of PSV with polyarticular involvement in a child is presented, and the differential diagnoses with other polyarthritis are offered. Synovial biopsy of both knees at different ages showed the presence of PSV in a fourteen years old boy with a nine years history of painless swelling of wrist, knees and ankles. Painless polyarticular swelling with few inflammatory signs, negative acute-phase laboratory tests, normal synovial fluid, periarticular soft tissue swelling on plain films and a mandatory synovial biopsy are the diagnostic clues of this rare presentation.