Table 1 The HLH- 2004 criteria for diagnosis of HLH are depicted 

A molecular diagnosis in HLH-causative genes OR at least one affected sibling OR fulfillment of at least 5/8 of below diagnostic criteria:

Fever ≥ 38.5 C

Cytopenias affecting at least 2 of 3 lineages—Hemoglobin < 9 g/dL—Platelets < 100,000 per mL—Neutrophils < 1,000 per mL

Hypertriglyceridemia (fasting: > 265 mg/dL) or hypofibrinogenemia (< 150 mg/Dl)

Splenomegaly

Ferritin > 500 ng/ml

sIL- 2r (sCD25) > 2400 u/ml

Low or absent NK-cell activity

Hemophagocytosis in bone marrow or other tissue