Arthritis seems, Juvenile idiopathic arthritis is not

When caring for children suffering articular pain or swelling, we must consider a wide differential diagnosis including trauma, infections, rheumatological diseases and neoplasms. Musculoskeletal complaints can be the first symptom of a leukemia in up to 20-30% of cases, sometimes as the only first symptom, causing delays on the diagnosis. We present the case of a 13 years old boy suffering several joint arthritis, with atypical evolution, who was finally diagnosed with Acute Linfoblastic Leukemia.