Table 2.

Diagnostic criteria for hemophagocytic syndrome according to trial HLH-2004

Confirmed molecular disease:	PRF1 mutation, UNC13D, Munc 18-2, Rab27a, STX11, SH2D1A, BIRC4
Five of eight clinical and laboratory criteria:	1. Fever
	2. Splenomegaly
	3. Cytopenia affecting two or more cell lines:
	• Hemoglobin <9g/dL
	• Platelets <100,000/mL
	• Neutrophils <1000/mL
	4. Hypertriglyceridemia (fasting triglycerides >265mg/dL or 3mMol/L) and or hypofibrinogenemia (<150mg/dL)
	5. Hemophagocytosis in bone marrow, spleen, liver, lymph node, skin
	6. Decreased or absent natural killer cell activity
	7. Ferritin >500ng/mL^a
	8. Soluble CD25 >2400U/mL

^aFerritin greater than 10,000ng/mL is almost confirmatory.