PSEUDOMALIGNANT VILLONODULAR SYNOVITIS: TEN CASES

Abstract

Purpose: Villonodular synovitis is a highly proteiform disease. The classical localisation is in the hand joints, but we focused on pseudomalignant forms which must be recognised to avoid unnecessarily aggressive treatment.

Material and methods: This series included ten files of patients seen for soft tissue tumour of the knee (n=6) or the hip (n=4). Time from first clinical sign to first consultation was two years on the average. The clinical presentation was dominated by major tumefaction of the soft tissues in all patients. There were no signs of joint disease in about half the patients. Radiological signs were noted in six patients. When obtained, MRI demonstrated, in all cases, a tumour formation with ferric deposits and thus contributed considerably to diagnosis.

Results: All patients underwent surgery. Five developed recurrence, as many as four times. One of these recurrent episodes was noted 17 years after the initial intervention that was considered satisfactory (wide monobloc resection). Joint involvement was minimal in these patients with a strong discordance between the minimally troublesome clinical presentation and the major anatomic modifications revealed radiographically.

Discussion: The risk of misdiagnosis is illustrated in our series which included two patients proposed for amputation with one which was actually performed due to a doubtful diagnosis of synovialosarcoma. This observation points out the review of the Swedish registry of synovialosarcomas: of the 81 files enrolled in the registry, 12 were found to be an aggressive form of villonodular synovitis.

Conclusion: The diagnosis of synovialosarcome, considered in patients who present with major tumefaction of soft tissues, signs of joint involvement, or ferric deposits identified on the MRI, should be evaluated with excessive care to rule out possible villonodular synovitis which responds to minimally aggressive treatment to be adapted to each individual case.