[Pigmented villonodular synovitis in children: review of six cases]

Pigmented villonodular synovitis is an exceptional condition in children. The clinical, biological and imaging presentation is not specific and a histology sample is required for certain diagnosis. Because of this lack of specificity, together with the rare occurrence of the disease, late diagnosis is not uncommon, making correct management an even greater challenge in the growing child.

Between 1995 and 2001, six children were treated for pigmentary villonodular synovitis, four girls and two boys, mean age 11.5 years. The knee was involved in five cases (three diffuse forms and two localized forms). One diffuse form involved the ankle. The diagnosis was suggested by the MRI findings in all patients and confirmed at the histological examination of a biopsy sample. Surgery was used in five cases and medical treatment in one patient with a diffuse form affecting the knee. A synoviorthesis (Hexatrione) was used systematically in three diffuse forms affecting the knee joint.

Mean follow-up was 58 months. Recurrence was noted in two diffuse forms, one involving the knee at 10 months from arthroscopic synovectomy and one involving the ankle 24 months after surgical synovectomy. Systematic use of the synoviorthesis did not prevent recurrence in one case. The synoviorthesis was also used in the two cases of recurrence as a complement to surgical treatment but with no effect. Growth was not affected in any of the children.

The etiopathogenic mechanism underpinning pigmented villonodular synovitis remains unclear. Genetic factors are suspected in childhood cases. MRI is the complementary examination of choice for diagnosis and follow-up. In children, treatment of pigmented villonodular synovitis depends on marginal excision of the lesion for localized forms and total synovectomy for the diffuse forms. The efficacy of the triamcinolone hexacetonide synoviorthesis remains open to debate and would require a larger series with longer follow-up for evaluation.