Localized pigmented villonodular synovitis of the knee joint: Neoplasm or reactive granuloma? A review of 18 cases

Abstract

Objective. The localized form of pigmented villonodular synovitis of the knee joint is a rare disease with limited alteration of the synovial membrane, the pathogenesis of which is the subject of controversial discussion. Methods. Eighteen cases have been documented in our hospital since 1976. All of the patients had additional cartilage or meniscus damage. Treatment consisted of excision of the lesion and the adjacent synovial membrane, as well as therapy of the additional damage. Results. The patients who had received such therapy were followed for 3-9 yr, without any clinical, sonographic or magnetic resonance tomographic signs of recurrence. In addition to the lack of a tendency towards recurrence, none of the cases displayed any further characteristics of the diffuse form of villonodular synovitis, such as invasiveness or malignant transformation. Conclusions. We therefore suggest that pigmented villonodular synovitis of the knee joint should be classified more strictly than before into a potentially neoplastic (diffuse) form and a reactive granulomatous (local) form. From the cases observed, we conclude that degenerative joint lesions may be the cause of the reactive granulomatous form.