Musculoskeletal pain and nonspecific symptoms are often the initial signs of cancer in about 20% of children who develop pediatric leukemia. Because of similar symptoms, childhood leukemia can masquerade as juvenile idiopathic arthritis, osteomyelitis, transient synovitis, or septic arthritis, resulting in delayed treatment.
What is leukemia?
Leukemia is a type of cancer that causes bone marrow to produce large numbers of abnormal white blood cells that enter the bloodstream and do not function properly. Leukemia accounts for 33-41% of all malignancies in children under 15 years of age with approximately 3250 children diagnosed each year in the United States.
Each type of leukemia is named for the blood cell that’s affected. The four most common types of leukemia are acute myeloid leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myeloid leukemia (CML), and chronic lymphocytic leukemia (CLL). Acute lymphoblastic leukemia (ALL) represents about 75-85% of all cases of childhood leukemia and is the form which is known to mimic arthritis. Symptoms are often vague and nonspecific.
Common leukemia signs and symptoms include:
• Fever or chills
• Persistent fatigue, weakness
• Frequent or severe infections
• Losing weight without trying
• Swollen lymph nodes, enlarged liver or spleen
• Easy bleeding or bruising
• Recurrent nosebleeds
• Tiny red spots in your skin (petechiae)
• Excessive sweating, especially at night
• Bone pain or tenderness
• Hematological abnormalities (anemia, low white blood cell count, low platelet count, circulating blasts)
How does leukemia look like juvenile arthritis?
Musculoskeletal symptoms are the primary complaint in 14% to 30% of pediatric ALL cases, sometimes before changes in peripheral blood are evident. Several case reports exist in the medical literature discussing patients who are initially (mis)diagnosed with juvenile idiopathic arthritis (JIA) due to bone pain and joint swelling, often in the lower extremities (ankle, knee, hip), to later be diagnosed with ALL. About 7% of children with ALL who initially have musculoskeletal manifestations meet diagnostic criteria for JIA.
What are the best ways to distinguish leukemia from arthritis in children?
Studies have identified three important features that predict a diagnosis of ALL and differentiate it from JIA, including:
• Low white blood cell count (leukopenia)
• Low-normal platelet count (thrombocytopenia)
• Nocturnal pain
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Childhood Leukemia Mistaken for Juvenile Rheumatoid Arthritis