What this Trial Is About

Background: Hemophagocytic lymphohistiocytosis (HLH) is a disease caused by disrupted immune function. People with HLH are prone to fevers and illnesses, which can be fatal. Some people develop a genetic form of this disease (pHLH), but researchers do not understand why some other people develop a nongenetic form (sHLH). They also do not have good ways to diagnose and treat sHLH. Objective: To learn about sHLH and why some people get it and others do not. Eligibility: Adults aged 18 years and older with sHLH. Design: Participants will be admitted to the study based on a review of their medical records. Those who join will have at least 3 clinical evaluations over 9 to 12 months. These may occur during an inpatient hospitalization if they require medical care or in the outpatient clinic. Participants will also have a physical exam at each visit. Up to half a cup of blood will be drawn at each visit. Participants may also have their blood drawn by their own doctors, who will send the samples to the researchers. Researchers may also contact these participants by telephone or video calls. The blood will be used for clinical tests as well as research. No new treatments will be administered as part of this study; however, standard medications and treatments may be recommended. Participants may opt to continue their visits once a year for 3 more years. Participants may also opt for an extra clinial evaluation 1 week after starting a new treatment. ...

Hemophagocytic Lymphohistiocytosis (HLH) Evaluation and Research of Clinical, ImmUnoLogic and TranscriptomE Study