Hemophagocytic Lympho Histiocytosis (HLH)

Hemophagocytic lymphohistiocytosis (HLH) is a rare immune system disease and is a life-threatening syndrome of excessive immune activation. Children may inherit the disease through genes; familial HLH. But in adults, many conditions can cause HLH; acquired HLH. It can be caused by some infections (viral infections, most often Epstein-Barr virus, other infections from bacteria or fungi), cancer (such as T-cell lymphoma), medicines that suppress the immune system and autoimmune diseases .

Diagnostic criteria:

1. A molecular diagnosis consistent with HLH. These include the identification of pathologic mutations of PRF1, UNC13D, or STX11.


2. Fulfillment of five out of the eight criteria below:

      *  Fever (defined as a temperature >100.3 °F, >38 °C)
      *  Enlargement of the spleen
      *  Decreased blood cell counts affecting at least two of three lineages in the peripheral blood:
                   *  Haemoglobin <9 g/100 ml / 5,6 mmol/L (in infants <4 weeks: haemoglobin <10 g/100 ml / 6,4 mmonl/L) (anemia)
                   *  Platelets <100×109/L (thrombocytopenia)
                   *  Neutrophils <1×109/L (neutropenia)
      *  High blood levels of triglycerides (fasting, greater than or equal to 265 mg/100 ml) and/or decreased amounts of fibrinogen in the blood (≤ 150 mg/100 ml)
      *  Ferritin ≥ 500 ng/ml
      *  Haemophagocytosis in the bone marrow, spleen or lymph nodes
      *  Low or absent natural killer cell activity
      *  Soluble CD25 (soluble IL-2 receptor) >2400 U/ml (or per local reference laboratory)