[Hemopigmented villonodular synovitis of the knee. Apropos of 2 cases]

We report two cases of hemopigmented villonodular synovitis in two girls aged 5 years 9 months and 13 years respectively. This condition is a clinicopathologic entity of unknown pathogenesis and is exceedingly rare in childhood. Patients of both sexes can be affected, with no particular predominance. The clinical picture in our two patients consisted only in chronic hemarthrosis of the knee with occasionally tumor-like features. Arthrographic changes were not specific. Diagnosis was established upon arthrography and results of pathologic studies of biopsy specimens. Therapy of this condition is surgical and recurrences are infrequent.