Pigmented Villonodular Synovitis Presenting as a Popliteal Cyst in a Child

Popliteal cysts occur relatively frequent!y in children and either are asymptomatic or are accompanied by slight pain after activity. Since popliteal cysts usual!y resolve spontaneously, most authors have recommended that such lesions be treated with observation69”522. The diagnosis of a popliteal cyst is made by a process of exclusion25’9. We report the case of a child who was thought to have a popliteal cyst over the medial head of the gastrocnemius muscle. Subsequent evaluation, how-ever, supported the diagnosis of pigmented villonodular synovitis. Case Report A ten-year and eleven-month-old boy had a three-month history of a gradually enlarging mass in the left popliteal fossa when he was first seen by us. He had mild pain after prolonged physical activity, bu