Secondary hemophagocytic lymphohistiocytosis in adults: an update on diagnosis and therapy.

Hemophagocytic lymphohistiocytosis (HLH), also known as hemophagocytic syndrome (HPS), is a rare, life-threatening, hematologic disorder manifested by clinical findings of extreme inflammation and unregulated immune activation. In both its congenital (primary) and adult (secondary) forms, it is most often characterized by fevers, hepatomegaly or splenomegaly, and bi- or trilineage cytopenias. In addition, elevated liver enzymes, hyperferritinemia, hypertriglyceridemia, and hypofibrinogenemia are commonly seen in HLH patients. A high index of suspicion is necessary for early diagnosis. Furthermore, a thorough diagnostic evaluation is necessary, and prompt treatment of the underlying causes is key in order to prevent irreversible tissue damage. Here we discuss the clinical signs, diagnosis, and treatments associated with this rare and potentially lethal disorder as manifested in adults.