Abstract
Primary familial hemophagocytic lymphohistiocytosis (HLH; or familial erythrophagocytic lymphohistiocytosis [FEL]) is a heterogeneous autosomal recessive disorder more prevalent with parental consanguinity. There is aggressive proliferation of activated macrophages and histiocytes, which phagocytose red blood cells (RBCs), white blood cells (WBCs), and platelets, leading to anemia, neutropenia and thrombocytopenia. The exaggerated response of immune system in familial HLH can occur in the absence of infection. We report on two Saudi siblings with familial hemophagocytic lymphohistiocytosis. The first case was diagnosed and started on treatment but died after ten days of treatment while the second one was referred to a higher centre for treatment but died before commencing chemotherapy treatment. This rare inherited aggressive disease needs high index of suspicion and early treatment. Anti-inflammatory therapy consisting of steroids, etoposide or antithymocyte globulin (ATG), should be instituted promptly, followed by curative hematopoietic cell transplantation to get a better outcome. Without treatment, most patients with familial hemophagocytic lymphohistiocytosis survive only a few months.

Key words: Antithymocyte globulin; Bone marrow; Child; Hemophagocytic lymphohistiocytosis; Paracentesis; Saudi Arabia