The Case of Kawasaki Disease after Rituximab Infusion Triggered by Human Anti-Chimeric Antibodies.

Rituximab (RTX) is an effective treatment for refractory nephrotic syndrome (NS), but may produce human anti-chimeric antibodies (HACA) which can cause severe infusion reaction or rituximab-induced serum sickness (RISS). RISS presents with a fever, rash, and arthralgia, which typically occurs 7–21 days after RTX infusion. On the other hand, Kawasaki disease (KD) also presents with fever and rash. There have been no reports of KD developed after RTX infusion. A 6-year-old girl with frequently relapsing NS was admitted to our hospital for fever and rash on day 7 after receiving RTX. Although it was suggestive of RISS at first, she also had conjunctival hyperemia, swelling, and erythema of the hands and feet, and a right coronary artery abnormality on echocardiography. Her symptoms met the diagnostic criteria of KD. We administered intravenous immunoglobulin (IVIg) (2 g/kg), and her symptoms resolved within a few days. The HACA titer determined using the serum collected at admission was very high. This is the first report of KD with a clinical course similar to RISS. It should be noted that a careful follow-up of coronary arteries should be performed in patients suspected of RISS.