Acute lymphoblastic leukemia masquerading as juvenile rheumatoid arthritis: diagnostic pitfall and association with survival

Acute lymphoblastic leukemia (ALL) often presents with osteoarthritic manifestations which may lead to misdiagnosis with juvenile rheumatoid arthritis (JRA). This study was designed to identify ALL patients with initial diagnosis of JRA, compare their clinicolaboratory characteristics and outcome with other ALL patients treated at our center. Case records of 762 patients with ALL were analyzed. Information regarding the clinical-demographic profile, therapy and outcome were recorded. Of the children, 49 (6.4%) had initial presentation mimicking JRA. Asymmetric oligoarthritis was the most common pattern of joint involvement. Majority presented with fever, pallor, arthritis, night pain, and bone pain. None of the routine prognostic factors including age, gender, lymphadenopathy, hepatosplenomegaly, total leukocytes count (TLC), and platelet count were significantly associated with relapse/death. The mean symptom-presentation interval (SPI), hemoglobin was significantly higher whilst the TLC was significantly lower in these patients compared to other ALL patients. The 5 year overall-survival was better than other patients with ALL (p = 0.06, by logrank test). Significantly longer SPI in these patients underscores the need for prompt and early investigations to rule out ALL in patients of JRA with atypical features and pointers of ALL. Children with ALL-mimicking JRA may belong to a subgroup of ALL with a better prognosis.