Fast Five Quiz: Hemophagocytic Lymphohistiocytosis

Sarah K. Tasian, MD


June 19, 2020

Laboratory abnormalities occurring in patients with HLH include two or more cytopenias, hypofibrinogenemia, and hypertriglyceridemia.

ESR may be decreased in patients with HLH due to hypofibrinogenemia, whereas other acute phase reactant levels are frequently elevated—in some cases, dramatically. Serum ferritin is the acute phase reactant most associated with the disease and levels can be dramatically elevated in patients with new-onset HLH or recurrence ("flare"). Elevation in serum ferritin level is a component in the widely accepted HLH-2004 diagnostic criteria from the Histiocyte Society.

The pathologic finding of hemophagocytosis, or the consumption/internalization of erythrocytes, platelets, or white blood cells by macrophages, is identified by the presence of whole blood cells or blood cell fragments within macrophage cytoplasm. Examination of bone marrow, spleen, liver, or lymph nodes may reveal this finding in patients with HLH. However, the presence of hemophagocytosis on a biopsy specimen is not required for the diagnosis of HLH, and its absence also does not rule out the disease.

Learn more about the workup and diagnosis of HLH.


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