Hemophagocytic lymphohistiocytosis

Abstract

Hematol Oncol Stem Cell Ther 2(2) Second Quarter 2009 hemoncstem.edmgr.com 367 Hemophagocytic lymphohistiocytosis (HLH) is an unusual and rare syndrome characterized by fever, splenomegaly, pancytopenia, and the pathologic finding of hemophagocytosis (phagocytosis by macrophages of erythrocytes, leukocytes, platelets, and their precursors) in bone marrow and other tissues. HLH comprises two different forms, a primary1,2 and a secondary form.1,3 The primary autosomal recessive form, familial hemophagocytic lymphohistiocytosis (FHLH), is a fatal disease with a median survival of less than 2 months after diagnosis if untreated, and typically has its onset during infancy or early childhood. Family history is often negative since the disease is recessive. Importantly, the onset of FHL and bouts of the disease may be triggered by infections.2,4,5 Secondary HLH (sHLH) may develop as a result of strong immunological activation of the immune system, which may, for example, be caused by a severe infection. sHLH has been described in immunocompromized hosts in association with viral or bacterial infections, virus (infection) associated hemophagocytic syndrome (VAHS,or IAHS).3,6 sHLH may also develop during malignancies (malignancy-associated hemophagocytic syndrome, MAHS). It may be the presenting clinical picture and mask an underlying malignancy, or it may develop during the treatment for a known malignancy.3,4 We report a series of three cases of HLH diagnosed in our institution representing three different facets of HLH-FHLH, IAHS and MAHS. These three cases illustrate the diversity of this syndrome and highlight the possibility of a treatable cause for a sHLH.