Hemophagocytic Lymphohistioctosis: Advances

A recent medical progress report provides a concise update on hemophagocytic lymphohistiocytosis (HLH) (J Pediatr 2013; 163: 1253-59).

  • Table 1 summarizes the subtypes of HLH.
  • Atypical presentations include colitis and hypogammaglobulinemia.
  • Table 2 provides the diagnostic criteria.
  • The treatment approach is outlined as well.  In the short-term, with primary HLH, the goal is controlling the hyperinflammatory state (often with dexamethasone and etoposide).  The long-term goal aims to definitively correct the underlying genetic defect by allogeneic hematopoietic stem cell transplantation (HCT)

Other points:

  • A genetic diagnosis of familial HLH can be made in 40-80% of HLH cases with the identification of PRF1, UNC13D, STX11, and STXBP2 genes.
  • UNC13D are the predominant defects identified in Caucasians in U.S.
  • PRF1 is most common in African-American patients.
  • Ferritin remains an excellent screening tool.  A level >500 mcg/L is suggestive (but not specific) for HLH; a level >10,000 has much greater specificity (96%) along with fairly high sensitivity (90%).
  • HLH is commonly referred to as macrophage activation syndrome (MAS) in the setting of a rheumatologic illness.
  • There is no broad consensus on management of secondary HLH.  In MAS, therapy often includes pulsed steroids and/or cyclosporine.

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