Table 1.

Haemophagocytic lymphohistiocytosis (HLH)—2004 diagnostic criteria¹³

1. A molecular diagnosis consistent with HLH

2. At least five of the following criteria should be met:

Fever

Splenomegaly

Cytopenias (affecting ≥2 of 3 lineages in the peripheral blood)

Haemoglobin <90 g/L (haemoglobin <100 g/L in infants <4 weeks)

Platelets <100×109/L

Neutrophils <1.0×109/L

Hypertriglyceridaemia and/or hypofibrinogenaemia

Fasting triglycerides ≥3.0 mmol/L (ie, ≥265 mg/dL)

Fibrinogen ≤1.5 g/L

Hemophagocytosis in bone marrow or spleen or lymph nodes. No evidence of malignancy.

Low or no NK cell activity (according to local laboratory reference)

Ferritin ≥500 mg/L

sCD25 (ie, soluble IL-2 receptor) ≥2400 U/mL

NK, natural killer; sCD25, soluble CD25.