Table 1.

Diagnostic criteria of HLH.

1. Only for primary HLH
Defects of known causable genes
Positive family history
2. Clinical findings
Fever
Splenomegaly
Cytopenia: Hb <9.0 g/dl, platelets <100,000/μl, and neutrophils <1,000/μl
Hypertriglyceridemia and/or hypofibrinogenemia
High triglycerides >3.0 mmol/l
Low fibrinogen <150 mg/dl
Hemophagocytosis
3. Laboratory findings
Low NK cell activity
Hyperferritinemia (>500 ng/ml)
High sIL-2R (>2,400 U/ml)