Failure to distinguish systemic-onset juvenile idiopathic arthritis from incomplete Kawasaki disease in an infant.

In an infant, an initial diagnosis of incomplete Kawasaki disease was made according to the American Heart Association guidelines. However, the diagnosis of systemic-onset juvenile idiopathic arthritis was established later. Physicians need to recognize that systemic-onset juvenile idiopathic arthritis can be mistaken for incomplete Kawasaki disease, even when the guidelines are used.