title: Understanding organ dysfunction in hemophagocytic lymphohistiocytosis.
abstract: OBJECTIVE
  This review aims to help critical care clinicians maintain a high level of suspicion regarding the diagnosis of Hemophagocytic Histiolymphocytosis (HLH). It describes the clinical and laboratory features of HLH, outlines its pathophysiology and reviews the most frequent etiologies related to HLH. Prognostic factors and therapeutic options are also reported.
  
  
  METHODS
  Review of the literature.
  
  
  RESULTS
  The diagnosis of HLH relies on the association of clinical abnormalities and hemophagocytosis in bone marrow, spleen, or lymph node specimens. Liver, pulmonary, renal, cardiac and skin involvement may occur at various degrees possibly leading to multiple organ failure. Three main etiologies can be found, namely infections, lymphoproliferative diseases, or connective tissue diseases. Immune deficiency is often retrieved. Mortality can be as high as 50%. Although clinically mimicking severe sepsis, HLH has a distinct pathophysiology on which specific therapy is based. Early diagnosis and treatment is mandatory to increase the chances of survival.
  
  
  CONCLUSIONS
  The comprehensive management of severe HLH requires the involvement of a multidisciplinary team in order to determine the best therapeutic strategy and to identify the underlying cause.
authors.affiliation: Department of Clinical Immunology, AP-HP, University Paris-7 Diderot, 75010, Paris, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Créput
authors.forename: Lionel
authors.initials: L
authors.lastname: Galicier
authors.forename: Sophie
authors.initials: S
authors.lastname: Buyse
authors.forename: Elie
authors.initials: E
authors.lastname: Azoulay
mesh_terms: D006644:Histiocytes / Q000166:cytology / Q000473:pathology; D006801:Humans; D007239:Infections / Q000150:complications; D051359:Lymphohistiocytosis, Hemophagocytic / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology*; D011379:Prognosis; D018417:Th1 Cells / Q000378:metabolism*