Popliteal cyst accompanied by an intra-articular cartilage lesion in a child.

The case of an 11-year-old girl presenting with a symptomatic popliteal cyst is described. There was no previous knee trauma nor could any inflammation be found. On MRI a concomitant retropatellar cartilage lesion had been detected preoperatively and was confirmed and treated by arthroscopy. The prevalence and treatment of popliteal cysts in children are discussed. Whereas in adults popliteal cysts are generally accompanied by intra-articular lesions, the presence of a concomitant intraarticular lesion in children is an extremely rare finding. We conclude that intraarticular lesions in the presence of popliteal cysts might have been underestimated as most of the studies regarding popliteal cysts in children were undertaken before the advent of arthroscopy, ultrasound, or MRI.