Hemophagocytic Lymphohistiocytosis, Secondary

Abstract

Secondary hemophagocytic lymphohistiocytosis (HLH) is a group of diseases characterized by fever, splenohepatomegaly, pancytopenia, hypertriglyceridemia, hypofibrinogenemia, decreased natural killer cell activity, high ferritin value, high soluble interleukin-2 receptor value, and hemophagocytosis, which are induced or associated by infections, malignant tumors, or autoimmune diseases. In Eastern Asia, primary Epstein–Barr virus (EBV) infection is the most common cause of secondary HLH. Other common causes of secondary HLH are non-EBV viral infections (cytomegalovirus, adenovirus, herpes simplex virus, varicella–zoster virus, parvovirus B19, parainfluenza virus, influenza virus, etc.), malignant lymphoma, and juvenile idiopathic arthritis. Secondary HLH can develop in a wide range of age groups starting from children to seniors. Autoimmune diseases and infection-related HLH are common in children, whereas lymphoma-related HLH is common in seniors. Although EBV-HLH is a heterogeneous disorder with various symptoms ranging from mild to severe, early initiation of immunochemotherapy consisting of dexamethasone, cyclosporin A, and etoposide has been recommended for patients with moderate to severe EBV-HLH.