B Cell ALL with Pyrexia of Unknown Origin, Masquerading as Inflammatory Arthritis.

We present a young male, with long standing fever, weight loss, bone pains, hepatosplenomegaly, cytopenias and severe joint pains. With normal peripheral smear and predominant joints involvement, he was started on corticosteroids. The partial response prompted the physician to continue the steroids. After some time, however, joints and bony pains worsened. After referral to us, he was found to have multiple bony lytic lesions and peripheral smear suggested B cell ALL. So, presentation predominantly with musculoskeletal symptoms, a normal peripheral smear and a partial therapeutic response to steroids as treatment of Systemic Juvenile Idiopathic Arthritis, delayed the diagnosis significantly leading to complications. So through our report we would like to stress that suspecting and diagnosing leukaemia early is important to prevent complications and resistance to treatment. An early bone marrow examination should also be instituted as a standard of care in peripheral smear negative patients.