Synovial arteriovenous malformation masquerading as arthritis

Synovial arteriovenous malformation is rare. We present three children with recurrent monoarthritis secondary to synovial arteriovenous malformation. Two children underwent excision of arteriovenous malformation. Another child had diffuse arteriovenous malformation, which was inoperable. Synovial arteriovenous malformations should be considered in the differential diagnosis of monoarthritis, especially of the knee.