Leukemic Arthritis Mimicking Septic Arthritis in a Pediatric Patient.

Case: A 7-year-old girl presented with a painful effusion in her right knee, fever, and a negative joint aspirate. One week later, she presented again with an effusion in her left elbow, elevated inflammatory markers, and a joint aspirate that raised concerns for septic arthritis. Irrigation and debridement of the elbow were performed, and the cultures returned negative results. Subsequently, the child experienced ongoing migratory polyarthropathy over several months, which was ultimately identified as leukemia. The initiation of chemotherapy resolved her symptoms. Although the orthopaedic literature is limited, leukemic arthritis should be considered in the differential diagnosis for a pediatric patient with a painful, swollen joint, especially when symptoms migrate without a clear cause. Key Concepts: (1)Leukemic arthritis appears as a painful, swollen joint that is clinically similar to septic arthritis, based on both examination and serum and synovial laboratory values.(2)A prompt diagnosis of acute leukemia is essential as leukemic arthritis can be the first presenting symptom.(3)Recognizing and understanding leukemic arthritis is essential for orthopaedic providers to ensure the timely diagnosis of leukemia and prevent unnecessary procedures and surgeries for these children.