Hemophagocytic lymphohistiocytosis (HLH) in a 25-year-old presenting with multisystem organ failure.

Hemophagocytic lymphohistiocytosis (HLH) is a rare syndrome of extreme inflammation caused by pathologic activation of the immune system. Diagnosis of HLH is challenging as the clinical presentation is similar to common medical entities such as sepsis. When a source of the extreme inflammation is not found, HLH should be considered in the differential diagnosis. In HLH, inflammatory markers such as soluble CD25 and ferritin levels are elevated. Ferritin assay is widely available at most institutions; a level greater than 10,000 is highly suggestive of HLH.2 Delayed diagnosis and failure to initiate cytotoxic chemotherapy will result in a fatal outcome.