MAUI, HAWAII (FRONTLINE MEDICAL NEWS) – The first thing nonpediatric rheumatologists need to understand about a child who presents with rheumatic complaints is the importance of ruling out malignancy, Dr. Anne M. Stevens stressed at the 2016 Rheumatology Winter Clinical Symposium.

“This is something I think we in pediatric rheumatology worry about a lot more than adult rheumatologists: malignancy and how to distinguish it from rheumatic diseases,” said Dr. Stevens, a pediatric rheumatologist at Seattle Children’s Hospital and the University of Washington.

And with there being only about 250 pediatric rheumatologists in the entire United States, and a handful of states having none at all, it’s important that physicians in other specialties be familiar with key differences between pediatric and adult rheumatic diseases, she added.

A diverse group of malignancies in children and teens can present with swollen joints or other rheumatic features. One of the biggest red flags suggestive of an underlying malignancy is disproportionate pain, especially nonarticular bone pain or tenderness or back pain as a major presenting feature.

The source of this bone or back pain may be a reactive arthritis in response to local bony changes caused by an osteosarcoma or neuroblastoma, or malignant effusions as a result of leukemia or lymphoma, Dr. Stevens explained.

Other atypical features that get her thinking about the possibility of underlying malignancy rather than juvenile idiopathic arthritis include weight loss, night sweats, fatigue, fever, and night pain. Overall, young patients with an undetected cancer just seem sicker than those with rheumatic disease, she continued.

In a classic retrospective study of 29 children and teens who initially presented to pediatric rheumatologists at the University of British Columbia and were ultimately found to have malignancy, the most common provisional rheumatologic diagnosis was juvenile rheumatoid arthritis in 12 of the 29. Five patients were thought by referring physicians to have a connective tissue disease, and three each were believed to have discitis or spondyloarthropathy. Other provisional diagnoses included systemic lupus erythematosus in two patients; Kawasaki disease in two; and Lyme disease, mixed connective tissue disease, and dermatomyositis in one each.

The final diagnoses included leukemia in 13 patients, neuroblastoma in 6, lymphoma in 3, Ewing sarcoma in 3, and single cases of ependymoma, thalamic glioma, epithelioma, and sarcoma (J Pediatr. 1999 Jan;134[1]:53-7).

Working backwards, the investigators developed a set of clinical clues helpful in detecting malignancy. Nonarticular bone pain was a prominent presenting complaint in 20 of the 29, bone tenderness in 8, and back pain in 9.

“Bone tenderness is not seen in juvenile idiopathic arthritis at all, and children under about age 10 just don’t get low back pain. That really alerts us to malignancy concern,” Dr. Stevens said.

Night sweats were present in four patients, severe constitutional symptoms in nine.

Two patients had true juvenile idiopathic arthritis, so that finding doesn’t rule out malignancy.

Surprisingly, the CBC was normal in three-quarters of patients. Antinuclear antibody testing is not helpful, as it can be strongly positive in the setting of pediatric malignancy, but lactate dehydrogenase and uric acid tests are important in making the differential diagnosis.

If there are any surprising findings raising concerns about possible malignancy, a bone marrow biopsy is essential.

“We have a lot of fights with our hematologists when we’re trying to get a bone marrow biopsy and they say, ‘No, the CBC is normal so you don’t need a bone marrow biopsy.’ But you have to get that bone marrow biopsy. A strategy that works is for us to say, ‘Could you please include a note in the chart that it’s okay for us to give steroids because you’re sure it’s not a lymphoma?’ Then we usually get it scheduled for the next day,” Dr. Stevens said.

She reported having no relevant financial disclosures.