A

Without treatment, approximately 20–25 % of children with Kawasaki disease develop coronary artery aneurysms, making this the key feared complication [Taubert & Shulman, 1999, PMID 10392592]. Intravenous immunoglobulin is given to all patients early to prevent these aneurysms, lymph-node biopsy is not used diagnostically, and other childhood vasculitides (e.g., IgA vasculitis) are more common, so the other statements are incorrect.