Table 1. KD-MAS diagnosis: HLH-2004 diagnostic criteria [16] and 2016 MAS classification criteria [33]

HLH-2004	2016 MAS classification
Fever	-
Splenomegaly	-
Cytopenia ≥ 2 cell lines	-
Hemoglobin < 9.0 g/dL	-
Neutrophils < 1,000 /μL	(Any two of the following four criteria)
Platelets < 100,000 /μL	i) Platelet ≤ 181,000 /μL
(Elevated liver enzymes are supportive evidence)	ii) AST > 48 U/L
Triglycerides ≥ 265 mg/dL	iii) Triglycerides > 156 mg/dL
or fibrinogen ≤ 150 mg/dL	iv) Fibrinogen ≤ 360 mg/dL
Ferritin ≥ 500 ng/mL	Ferritin > 684 ng/mL (essential)
sCD25 (soluble IL-2 receptors) ≥ 2,400 U/mL	-
Decrease or absent NK cell activity	-
Hemophagocytosis in bone marrow, liver, or lymph nodes	-
Diagnosed when ≥ 5/8 criteria are met	Diagnosed when hyperferritinemia + ≥ 2/4 criteria

KD-MAS: Kawasaki disease complicated with macrophage activation syndrome; HLH: hemophagocytic lymphohistiocytosis; MAS: macrophage activation syndrome; -: not applicable; AST: aspartate aminotransferase; IL-2: interleukin-2; NK: natural killer.