Contemporary Pediatrics - September 2008 - (Page 44)

Puzzler Table 1 What could this be? The differential diagnosis of his leg pain was vast (Table 1). It included rheumatologic problems (poststreptococcal reactive arthritis, rheumatic fever, Reiter’s syndrome, systemic lupus erythematosis, chronic recurrent multifocal osteomyelitis, or juvenile idiopathic arthritis), orthopedic problems (bursitis, tendonitis, ligamentous injury, fracture), infectious processes (viral arthritis, septic arthritis, Lyme disease, osteomyelitis), and malignancy (leukemia, metastatic disease, osteosarcoma, Ewing’s sarcoma, and benign bony tumors). Most rheumatologic problems were less likely, since RF, ANA, HLA-B27, ESR, and CRP were all normal. Acute rheumatic fever was unlikely, since his arthritis was not typical of the migratory arthritis of ARF. Plus, other than evidence of a recent streptococcal infection he did not meet any other Jones criteria. PSRA was still a possibility. The likelihood of an orthopedic problem seemed low since radiographs had ruled out fractures or any lytic lesions, and rest, ice, and ibuprofen had no effect on the pain You continue to wonder why this previously healthy 8-year-old has osteopenia. His pain was worsening even though he was completely non-weightbearing for the last five days. Infectious processes were unlikely, since he never had fever or an increased WBC (white blood cell) count, and otherwise looked well. He had no history of prior infection or insect bites. At this point, PSRA and malignancy were the highest on your differential. His ASO titers pointed you to PSRA. It was an obvious diagnosis, yet his clinical picture did not fully support it. Upon admission to the hospital, he had an MRI of his lower extremities. It showed marked decreased T1 and increased T2 signal in the metaphyses of bilateral distal femurs and proximal tibia, which enhanced when contrast was administered (Figure 1). Mild abnormal signal was seen in bilateral proximal femurs, ischia, and pubic bones. There was also some enhancement of the muscles surrounding the tibias. This raised the suspicion of an infiltrative process such as leukemia or metastatic disease from neuroblastoma. These concerns prompted the referral to the >> p.46 oncologic service, to rule out a malignancy. Differential diagnosis of leg pain Connective tissue disorders • • • • • • • • • Poststreptococcal reactive arthritis Rheumatic fever Reiter’s syndrome Systemic lupus erythematosis Chronic recurrent osteomyelitis Juvenile idiopathic arthritis Trauma/abuse Fractures Bursitis Tendonitis Viral arthritis Septic arthritis Lyme arthritis Osteomyelitis Leukemia Metastic disease Osteosarcoma Emings sarcoma Benign bone tumors and lesions (eg, osteoid osteoma) Orthopedic disorders • • • • Infectious processes • • • • • • • • • • Malignancies Metabolic • Vitamin C deficiency • Vitamin A toxicity • Heavy metal toxicity ties associated with rheumatic fever. No abnormalities were found. A rheumatologist was consulted and agreed that this might be PSRA. He was able to ambulate before leaving the ED, and was sent home to be seen in the rheumatologist’s office the next day. Over the next week he tried naproxen for pain without any relief, and was switched to indomethacin. After several days on this anti-inflammatory, the pain was still getting worse. His mother desperately called the office reporting that he was again refusing to walk, and had missed the last five days of school. She had resorted to carrying him around the house. At this point, it was decided that he should be admitted to the hospital for further evaluation. 44 www.contemporarypediatrics.com Vol. 25, No. 9 http://www.contemporarypediatrics.com

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Contemporary Pediatrics - September 2008 Contents Editorial Your Voice Clinical Tip News Updates Eye on Washington Puzzler Dermatology: What’s your Dx? Behavior Cover Story: ECC Epidemic Parent Guides Discipline Techniques: The 12-Month-Old Exercise-induced Bronchospasm: Keeping Our Patients Active Food Safety Parent Guide CPR--Food Safety Malnutrition Links Surgeon General Links Hospice Links Childhood Cancer Links Rx for a Healthy Practice Rx for a Healthy Practice New Products Author Guidelines Journal Club Events Calendar Classifieds Index of Advertisers Postscript

Contemporary Pediatrics - September 2008

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