Enthesitis as Initial Manifestation of Leukemia in a Pediatric Patient - Abstract
This case report highlights the importance of working through a differential diagnosis when a child presents with arthritis or enthesitis, as Juvenile Idiopathic Arthritis (JIA) is a diagnosis of exclusion. A twelve-year-old girl presented to clinic with chronic arthralgias, most notably in her ankles. Some of her symptomatology was characteristic of inflammatory arthritis - morning stiffness and limp. However, the pain was also worse with activity, better with rest, and with occasional night awakenings. Her physical exam revealed no arthritis but she did have enthesitis with swelling, warmth and tenderness over her posterior-lateral malleolus. Nonsteroidal anti-inflammatory drug (NSAID) therapy was started and she had blood work to further investigate the etiology of her enthesitis. Diagnostic considerations were concerning for HLA B27 associated enthesitis related arthritis, psoriatic JIA, Inflammatory bowel disease and
chronic recurrent multifocal osteomyelitis. Laboratory findings showed elevated ESR and CRP consistent with inflammation. HLA B27, Rheumatoid Factor and ANA were negative. Her blood count showed mild leukocytosis and anemia. Her differential revealed 17% atypical lymphocytes and 30% blasts. LDH was 251 u/l [normal range 98-192u/l] and uric acid was 6.9 mg/dl [normal range 2.5-7.0mg/dl]. Her peripheral smear showed increased circulating blasts and flow cytometry was consistent with B cell Acute Lymphoblastic Leukemia. The importance of this case is to remember that musculoskeletal symptoms may precede constitutional symptoms in children with leukemia. Thus, it is essential to rule out other differentials prior to diagnosing JIA, especially prior to initiation of steroid or immunosuppressive therapies.