Pediatric Rheumatology Online Journal

Vol 2, No. 2   2004

http://www.pedrheumonlinejournal.org

Answer to Previous Fellow's Challenge Case

The diagnosis of the 8 year old girl who presented with musculoskeletal pain (volume 2, number 1) is acute lymphoblastic leukemia (ALL). The child had several clinical features present which would raise concern of malignancy. Firstly, her pain was out of proportion to the objective physical findings. Additionally, her musculoskeletal pain complaints were not confined to the joints, but were present also in the long bones, a finding suggestive of malignancy as opposed to JIA. Furthermore, the pain awakened her at night. Night pain is much more common in malignancy than JIA. In a retrospective multi-center study evaluating the presentation of ALL versus JIA, 65% of children with ALL had night-time pain, compared to 17% with JIA (manuscript in preparation).

The child's laboratory results further increased suspicion of ALL.

Her platelet count decreased from 500,000 to 310,000 while the sedimentation rate increased slightly from 52 to 65. Even though the platelet count still remained well within normal limits, platelet decrease in the presence of increasing acute phase protein level is concerning. This dissociation of inflammatory indices (increased ESR with normal to low platelet counts) has been observed in ALL. The patient also had depression of two cell lines on her CBC (WBC 4.0; hemoglobin 9.4). Although anemia is not uncommon in JIA, especially systemic onset, a low WBC count is rarely reported. The absence of blasts in the peripheral blood may be expected in a child referred to a rheumatologist for evaluation of musculoskeletal pain. In our unpublished data, 75% of the ALL children presenting to the rheumatology clinic did not have blasts on the CBC. Other laboratory results which may increase concern for ALL include elevated LDH and/or uric acid (not available on this patient).

The child's radiograph showed osteolytic changes and marked periostial reaction along the fibula. The differential diagnosis for this diaphysial lesion includes Ewing's sarcoma, osteomyelitis and neuroblastoma. The suspicion for Ewing's sarcoma in this patient was low because of the presence of diffuse musculoskeletal complaints. Chronic recurrent multifocal osteomyelitis (CRMO) could be considered in this patient based on the x-ray findings, multi-focal bone pain, anemia and elevated sedimentation rate. However, the presence of joint swelling and limitation in range, seen in our patient, would not be expected in CRMO. Metastatic neuroblastoma may present with multifocal bone and joint complaints, often with pain disproportionate to physical findings. However, neuroblastoma is a malignancy of early childhood, and would be distinctly uncommon in an 8 year old child.

Radiographs in children with ALL may be normal. Others will show demineralization, lytic lesions and periosteal reaction, as seen in this patient. The presence of metaphyseal rarefaction (or radiolucent bands) should raise the suspicion of acute leukemia.

Fellows' responses to this challenge:

ALL - 50%

CRMO - 37.5%

Neuroblastoma - 12.5%

The winner (based on the first correct response received) is:

Christine Bernal, M.D.

Pediatric Rheumatology

Fellow Baylor College of Medicine

Linda Wagner-Weiner, M.D.