Macrophage activation syndrome in Kawasaki disease: a literature review of Korean studies.

Macrophage activation syndrome (MAS) is a rare but potentially life-threatening complication of Kawasaki disease (KD). In Korea, many studies on KD have been reported, but there are only a few studies on MAS complicating KD (MAS-KD). This study was conducted to provide the characteristics of MAS-KD patients in Korea through a literature review. A total of 23 Korean patients with MAS-KD from 10 papers were included in this study. All MAS-KD patients met the hemophagocytic lymphohistiocytosis (HLH)-2004 criteria and/or the 2016 MAS criteria. The incidence of MAS-KD in Korean children was 0.8%~1.1%, which is relatively low compared to North America (1.9%). MAS-KD patients had lower rates of KD-related features and higher rates of incomplete KD, coronary artery abnormalities, and intravenous immunoglobulin resistance than patients with KD without MAS. Notable laboratory abnormalities in MAS-KD include anemia, neutropenia, thrombocytopenia, hypoalbuminemia, increased hepatic transaminase levels, and hyperferritinemia. For treatment of MAS-KD, the HLH-2004 protocol (i.e., 40 weeks of complex chemotherapy) was applied to 15 patients (65%), which is a significantly greater than those treated with this protocol in other countries (35%). Two patients (9%) died during the HLH-2004 protocol. In actual practice, MAS may be underrecognized in patients with KD. Clinical suspicion is paramount for early diagnosis and timely treatment.