What is the prognosis of HLH? What are the poor prognostic factors?

  • Primary HLH is almost universally fatal without treatment
  • Mortality improved with treatment
  • Approximately 50% with HLH-94 based treatment
  • Secondary HLH and HLH in adults without treatment has high mortality:
  • Overall mortality of 50% to 75%
  • Stem cell transplant has resulted in significant improvements in long term survival and cure
  • Younger age
  • CNS involvement
  • Failure of therapy to induce a remission before HCT
  • Association with malignancy