HLH
Meaning of HLH: Hemophagocytic lymphohistiocytosis, abbreviated HLH, is a rare condition of excessive immune activation that damages organs and destroys blood cells.
Definition of HLH
HLH is the abbreviation for hemophagocytic lymphohistiocytosis, a rare and serious condition in which certain immune cells, including histiocytes and lymphocytes, become abnormally overactive and trigger widespread inflammation throughout the body. Activated histiocytes engulf other blood cells, contributing to low blood counts, and organs such as the liver, spleen, and bone marrow are commonly affected.
HLH occurs in two general forms. A primary or familial form arises from an inherited genetic change affecting how immune cells regulate themselves and typically appears in infancy or early childhood, while a secondary form develops later in life, triggered by an infection, cancer, or autoimmune disease that provokes the same excessive immune response.
Because HLH affects multiple organ systems through this widespread immune overactivation, it commonly presents with persistent fever, an enlarged liver and spleen, low blood counts, and abnormal clotting, and its rapid progression makes early recognition an important part of evaluation.
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Used in a sentence
Laboratory findings supported a diagnosis of HLH after the patient presented with persistent fever and an enlarged spleen.
Good to know
HLH can closely resemble severe sepsis or another systemic infection at first presentation, since persistent fever and multi organ involvement overlap considerably with more common serious illnesses.