Hemophagocytic lymphohistiocytosis (HLH) is a term used to describe a life-threatening hyper-inflammatory syndrome. HLH is characterized by persistent fevers, rash, hepatosplenomegaly, cytopenias, coagulopathy, hepatitis / liver failure, and if there is central nervous system involvement, altered mental status, neurologic deficits, and seizures.
Once a diagnosis of HLH is established, treatment should be started immediately. Treatment is often based on the HLH-94 protocol, and includes dexamethasone and etoposide. Alternatively, treatment may include anti-thymocyte globulin in lieu of etoposide. Cyclosporine is also sometimes used. Some patients require additional “salvage” agents such as alemtuzumab.
While patients are undergoing treatment, efforts should be made to determine if there is a genetic defect present. Screening tests may help to guide genetic testing in a logical manner. If a genetic defect is observed, curative treatment with allogeneic hematopoietic cell transplantation should be considered. In the absence of a genetic diagnosis, transplant should also be considered for young patients and those with a family history, recurrent clinical phenotype, or functional laboratory studies suggesting an inherited defect in lymphocyte cytotoxicity.
> For complete information, see our publication in Blood, “How I treat hemophagocytic lymphohistiocytosis,” which offers a state-of-the-art review of HLH treatment.