Transient idiopathic periosteal reaction associated with dysproteinemia.

Periosteal reaction with new bone formation in a child is a radiographic finding with an extensive differential diagnosis. The present case is that of a child who presented with a clinical syndrome of fever, bone pain in the forearm and leg, bony tenderness in these areas, radiographic evidence of a periosteal reaction in both tibiae and ulnae, and an abnormality of serum proteins. It was a self-limited disease process requiring no specific treatment, with eventual return to normal of both the radiographic and serum protein abnormalities. Its relationship to Caffey's disease remains to be defined.