Abstract Hemophagocytic Lymphohistiocytosis (HLH) is a rare disorderofthe immune system,affecting macrophages that grow abnormally and accumulate in body organs which include liver, spleen, bone marrow, CNS and skin. There are 2 types of HLH:
Primary: An inherited condition where there is a genetic mutation in:
• Perforin (PRF-1)
• Gene encoding Munc 13-4 protein which alters the NK & Tcell function.
Secondary: Triggered by infections (viral, bacterial, fungal), autoimmune disorders, primary immune deficiencies or cancer.