Hemophagocytic lymphohistiocytosis

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Etiologies

Differential Diagnosis

Diagnostic Criteria (HLH-2004)

The diagnosis of HLH can be established if one of either 1 or 2 below is fulfilled:

  1. A molecular diagnosis consistent with HLH is made.
  2. Diagnostic criteria for HLH are fulfilled (5 of the 8 criteria below):*
    • Fever
    • Splenomegaly
    • Cytopenias (affecting ≥ 2-3 lineages in the peripheral blood):
      • hemoglobin < 90 g/L (in infants < 4 weeks of age, hemoglobin < 100 g/L)
      • platelets < 100x10^9^/L
      • neutrophils < 1.0x10^9^/L
    • Hypertriglyceridemia and/or hypofibrinogenemia:
      • fasting triglycerides ≥ 3.0 mmol/L (ie, ≥ 265 mg/dL)
      • fibrinogen ≤ 1.5 g/L
    • Hemophagocytosis in BM, spleen, or lymph nodes
    • Low or absent NK-cell activity (according to local laboratory reference)
    • Ferritin ≥ 500 g/L
    • Soluble CD25 (ie, sIL2r) 2400 U/mL†
  • Supportive criteria include neurologic symptoms, cerebrospinal fluid pleocytosis, conjugated hyperbilirubinemia and transaminitis, hypoalbuminemia, hyponatremia, elevated D-dimers, and lactate dehydrogenase (see text for details). The absence of hemophagocytosis in the BM does not exclude a diagnosis of HLH.

† New data show normal variation by age. Level should be compared with age-related norms.