Differences and similarities of multisystem inflammatory syndrome in children, Kawasaki disease and macrophage activating syndrome due to systemic juvenile idiopathic arthritis: a comparative study

Rheumatol Int. 2022 May;42(5):879-889. doi: 10.1007/s00296-021-04980-7. Epub 2021 Sep 7.


To compare the clinical and laboratory findings of multisystem inflammatory syndrome in children (MIS-C), patients with Kawasaki disease (KD) and with macrophage activating syndrome due to systemic juvenile idiopathic arthritis (sJIA-MAS) on real-life data. Patients diagnosed with MIS-C, KD, and sJIA-MAS from 12 different centers in Turkey who were followed for at least 6 months were included in the study. Demographic, clinical, and laboratory findings of all patients were analyzed. A total of 154 MIS-C, 59 KD, and 31 sJIA-MAS patients were included. The median age of patients with MIS-C were higher than those with KD while lower than those with sJIA-MAS (8.2, 3, 12 years, respectively). Myalgia (39.6%), cardiac (50.6%), gastrointestinal (72.7%), and neurological (22.1%) involvements were more common in patients with MIS-C compared to others. MIS-C patients had lower levels of lymphocyte (950 vs 1700 cells/µl) and thrombocyte (173,000 vs 355,000 cells/µl) counts and higher pro-BNP (1108 vs 55 pg/ml) levels than KD. Ferritin levels were higher in patients with MIS-C compared to patients with KD while they were lower than patients with sJIA-MAS (440, 170, 10,442 ng/ml, respectively). Patients with MIS-C had a shorter duration of hospitalization than sJIA-MAS (p = 0.02) while they required intensive care unit admission more frequently (55 vs 8 patients, p < 0.001). The median MAS/sJIA score of MIS-C patients was - 1.64 (- 5.23 to 9.68) and the median MAS/sJIA score of sJIA-MAS patients was -2.81 ([- 3.79] to [- 1.27]). MIS-C patients displayed certain differences in clinical and laboratory features when compared to KD and sJIA-MAS. Definition of the differences and similarities between MIS-C and the other intense inflammatory syndromes of childhood such as KD and MAS will help the clinicians while making timely diagnosis.

Keywords: Kawasaki disease (KD); Macrophage activation syndrome; Multisystem inflammatory syndrome in children (MIS-C); Systemic juvenile idiopathic arthritis.

MeSH terms

  • Arthritis, Juvenile* / complications
  • Arthritis, Juvenile* / diagnosis
  • Biomarkers
  • COVID-19 / complications
  • Child
  • Ferritins
  • Humans
  • Macrophage Activation Syndrome* / diagnosis
  • Macrophage Activation Syndrome* / etiology
  • Macrophages
  • Mucocutaneous Lymph Node Syndrome* / complications
  • Mucocutaneous Lymph Node Syndrome* / diagnosis
  • Systemic Inflammatory Response Syndrome


  • Biomarkers
  • Ferritins

Supplementary concepts

  • pediatric multisystem inflammatory disease, COVID-19 related