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.