Arthritic presentation of childhood malignancy: beware of normal blood counts.

Some children with malignancy (e.g. acute lymphoblastic leukemia) who initially present with musculoskeletal complaints may be misdiagnosed as having a rheumatological disorder. In the literature, importance has been given to subtle changes in blood counts, which may point toward an underlying malignancy. We report 3 children with malignancy, who had an arthritic presentation but had normal blood counts at presentation. Atypical clinical pattern, significant nocturnal pain, pain out of proportion to joint involvement and prominent systemic features in these children prompted us to do a bone marrow examination that revealed a malignancy. Pediatricians must be aware of the arthritic presentation of childhood malignancy. If the clinical features point toward a malignancy, bone marrow examination should always be performed even if the blood counts are normal.