[Pigmentous villonodular synovitis affecting the bone (author's transl)].

Pigmentous villonodular synovitis (P.V.N.S.) is a rare arthropathy consisting in a hypertrophic-hyperplastic reaction of the synovial membrane in circumscribed or diffused form. Involvement of the bond, found very rarely during the course of this arthropathy, seems to be due to compressive-erosive action of diffusely hyperplastic pathologic tissue and not neoplastic invasion. In this note there is a report on the cases of the "G. Pini" Orthopaedic Institute in Milan: 33 cases of P.V.N.S., of which 5 with bone involvement.