Multifocal pigmented villonodular synovitis in a child.

We describe the rare case of a 6-year-old girl with multifocal pigmented villonodular synovitis. The patient is only the sixth child less than or equal to 10 years of age reported in the literature and the youngest to experience multifocal involvement. She had lesions affecting the right knee and the synovium of the posterial tibial tendons proximal to the medial malleoli of both ankles. The history, differential diagnosis, and treatment of this disorder are discussed briefly.