Ganglion cysts of the knee are rare, but they can appear in cases of juvenile idiopathic arthritis (JIA). Magnetic resonance imaging (MRI) identifies them when there is persistent pain without swelling.
A 10-year-old girl with JIA diagnosed at 2 years of age presented with arthralgia and swelling of the right knee. She had been disease-free for 3 years, and JIA relapse was diagnosed. Methotrexate (MTX) was readministered, but arthritis …