Table 3. Hemophagocytic lymphohistiocytosis (HLH)-2004 diagnostic criteria. The diagnosis of HLH can be established if criterion 1 or 2 is fulfilled.

Source: [4]

Criterion	HLH Diagnostic Criteria
Criterion 1	A molecular diagnosis consistent with HLH
Criterion 2 (five of the following eight criteria)	1) Fever. 2) Splenomegaly. 3)Cytopenias (affecting ≥2 of 3 lineages in the peripheral blood): hemoglobin < 90 g/L (hemoglobin < 100 g/L in infants < 4 wk); platelets <100 ×109/L   neutrophils <1.0 ×109/L.  4) Hypertriglyceridemia and/or hypofibrinogenemia: fasting triglycerides ≥ 3.0 mmol/L (i.e., ≥ 265 mg/dL); fibrinogen ≤ 1.5 g/L. 5) Hemophagocytosis in the bone marrow or spleen or lymph nodes. No evidence of malignancy. 6) Low or no NK cell activity (according to local laboratory reference). 7) Ferritin ≥ 500 µg/L.  8) sCD25 (i.e., soluble IL-2 receptor) ≥ 2400 U/mL.
Supportive evidence	1) Cerebral symptoms with moderate pleocytosis and/or elevated protein. 2) Elevated transaminases. 3) Elevated bilirubin. 4) Elevated LDH.