Table 2.

Diagnostic criteria adapted from the HLH-2004 trial.

Molecular identification of an HLH-associated gene mutation (e.g. PRF1, UNC13D, STX11, STXBP2, Rab27A, SH2D1A, BIRC4, LYST, ITK, SLC7A7, XMEN, and HPS)

OR

Five of the following eight findings:

1. Fever ≥ 38.5℃

2. Splenomegaly

3. Peripheral blood cytopenia

4. Hypertriglyceridemia (fasting triglycerides >265 mg/dL) and/or hypofibrinogenaemia (fibrinogen < 150 mg/dL)

5. Haemophagocytosis in bone marrow, spleen, lymph node or liver

6. Low or absent NK cell activity

7. Ferritin > 500 ng/mL

8. Elevated soluble CD25 (soluble IL-2 receptor alpha) two standard deviations above age-adjusted laboratory-specific norms

Note: Adapted from Jordan et al.¹