Rheumatic disease mimics in childhood

Aches and pains in children can arise from multiple problems, varying from a reaction to minor intercurrent infection that rapidly improves to the presence of severe skeletal lesions such as malignancy; they can also be part of a skeletal dysplasia. All cases require a good history (including family history), a full examination, and basic blood tests, which include the erythrocyte sedimentation rate, hemoglobin, white count, platelets, rheumatoid factor, and antinuclear factor. Other tests need be performed only when suspicion has been aroused. Recognition of unusual syndromes is important; no child should be labeled as having juvenile idiopathic arthritis unless there is a clear history with the presence of soft tissue swelling in appropriate sites and other causes for joint pain have been excluded. The conditions that most frequently mimic systemic onset juvenile arthritis are infections, which may have been partially treated, inflammatory bowel disease, malignancy, familial Mediterranean Fever, and the rarer connective tissue diseases, in particular systemic lupus erythematosus. Bacterial infection should be suspected in a child who is feverish and toxic, with a single hot swollen joint that has limited movement and is often rigidly guarded. Should such a child have already received antibiotics, general symptoms may well be minimal, so one is left with the history and a swollen and painful joint. Aspiration for investigation of the synovial fluid as well as blood tests should be undertaken immediately to establish the nature of any underlying infection.