Childhood leukemia mimicking juvenile rheumatoid arthritis

Arthritis is a known manifestation of childhood leukemia. When it is the sole clinical finding, diagnosis of juvenile rheumatoid arthritis (JRA) may be impressed initially and hence delay diagnosis of the underlying malignancy. This review analysed the clinical pictures of six such patients whose acute lymphoblastic leukemia (ALL) was diagnosed after a variable period of delay, ranging from 2 weeks to 44 months. In general, initial articular and extra-articular symptoms, and responses to conventional treatment, are not helpful in differentiating leukemic arthropathy from juvenile rheumatoid arthritis. However, the six ALL patients did have significantly less leukocytosis (6834 +/- 1586 vs 13365 +/- 8039/mm3, p < 0.05) and relative lymphocytosis (61 +/- 17% vs 30 +/- 13%, p < 0.05) on the initial hemograms when compared with JRA patient findings. JRA patients with initial hemograms showing less leukocytosis and relative lymphocytosis should be followed up with a high index of suspicion. Work-up for leukemia should be performed in any JRA patient with an evolving hemogram showing anemia, thrombocytopenia, leukopenia and lymphocytosis. Those who have an intractable clinical course necessitating immunosuppressive therapy should also receive bone marrow examination to obviate confusion in interpreting follow-up laboratory data. It can not be overemphasized that the differential diagnosis of acute leukemia should be made before JRA is impressed.