Diagnostic difficulties in pigmented villonodular synovitis. Presentation of cases

Pigmented villonodular synovitis is a rare entity. There are limited and diffuse, intra- and extraarticular forms. In the literature, this condition has been called xanthoma, xanthogranuloma, villous arthritis, pigmented villonodular synovitis, xanthomatous giant cell tumour, giant cell tumour of tendon sheath, giant cell fibrohemangioma, benign synovioma. The paper presents two cases in which, due to ignorance of this disease, patients were primarily qualified for oncological treatment: chemotherapy and radical resection or limb amputation. In both cases synovectomy produced good clinical outcomes although the procedures were not radical. It is necessary to unify the naming of pigmented villonodular synovitis because various names can be misunderstood by clinicians. Investigations indicating a non-inflammatory aetiology and reports of potential malignancy suggest that the terms inflammation or synovitis should no longer be used.