| Primary HLH (Mendelian inherited conditions leading to HLH) (Table 4) |
| Defects in the cytolytic function of cytotoxic T cells and/or NK cells13,46,51 |
| Defects in inflammasome regulation122,123 |
| Secondary HLH (apparently non-Mendelian HLH)10 |
| Infections (mainly viruses, such as EBV, HIV, and CMV, but also bacteria, parasites, and fungi)14 |
| Malignancies (mainly malignant lymphoma)15 |
| Macrophage activation syndrome in autoinflammatory or autoimmune disorders111 |
| Other causes (organ or stem cell transplantation; metabolic, traumatic, iatrogenic [immunosuppression, vaccination, surgery, hemodialysis] causes; and, rarely, pregnancy)10,14 |
| Primary HLH (Mendelian inherited conditions leading to HLH) (Table 4) |
| Defects in the cytolytic function of cytotoxic T cells and/or NK cells13,46,51 |
| Defects in inflammasome regulation122,123 |
| Secondary HLH (apparently non-Mendelian HLH)10 |
| Infections (mainly viruses, such as EBV, HIV, and CMV, but also bacteria, parasites, and fungi)14 |
| Malignancies (mainly malignant lymphoma)15 |
| Macrophage activation syndrome in autoinflammatory or autoimmune disorders111 |
| Other causes (organ or stem cell transplantation; metabolic, traumatic, iatrogenic [immunosuppression, vaccination, surgery, hemodialysis] causes; and, rarely, pregnancy)10,14 |
CMV, cytomegalovirus; EBV, Epstein-Barr virus.