Diagnosis guide
Hemophagocytic lymphohistiocytosis (HLH)
Hemophagocytic lymphohistiocytosis (HLH) is a severe, life-threatening inflammation in which activated immune cells do not switch off. It has two broad forms. Primary (genetic) HLH, which includes familial HLH and the X-linked lymphoproliferative diseases, is caused by inherited gene changes and is most common in children. Secondary (acquired) HLH is more common in adults and is usually triggered by an infection, a cancer or an autoimmune disease, so treatment also targets the trigger. Urgent treatment calms the inflammation first. A donor stem cell transplant can cure primary HLH, and it is also considered for some people whose HLH comes back. The pages below cover the inherited forms.
In short
- HLH is a severe, life-threatening inflammation in which activated immune cells do not switch off and can damage organs.
- Primary HLH is inherited and most common in children; secondary HLH is usually triggered by an infection, a cancer or an autoimmune disease, mostly in adults.
- Urgent treatment calms the inflammation first, and a donor stem cell transplant can cure primary HLH.
Find the subtype on your report
The exact diagnosis shapes the treatment options. Your care team can explain the name on your report.
Familial HLH (hemophagocytic lymphohistiocytosis)
Familial hemophagocytic lymphohistiocytosis (familial HLH) is an inherited immune disorder in which immune activation does not switch off properly. It can cause severe inflammation and organ damage; it is not a blood cancer.
Donor transplant optionX-linked lymphoproliferative disease type 1 (XLP1)
XLP1 is an SH2D1A-related immune-regulation disorder. It can cause life-threatening inflammatory illness such as HLH, abnormal antibody levels and lymphoma; Epstein–Barr virus is an important trigger, although disease is not limited to one infection.
Donor transplant optionXIAP deficiency (XLP2)
XIAP deficiency is an X-linked disorder of immune regulation, historically called XLP2. It can cause HLH, recurrent inflammation and inflammatory bowel disease, including illness that is not triggered by Epstein–Barr virus.
Donor transplant option
Support for patients and families
These independent organizations offer information and support. JBF is not affiliated with them.
- Histiocytosis Association Global nonprofit for histiocytic disorders, including HLH, dedicated to the needs of patients and families and to research toward a cure.Worldwide
- HLH Heroes Foundation U.S. nonprofit started by HLH caregivers, offering hospital care packages, connections with other HLH families and financial help.United States
- Histio UK UK charity for histiocytic disorders, including HLH, that supports patients and families and raises awareness among the public and professionals.United Kingdom
Someone may be waiting for a match.
Some people with hemophagocytic lymphohistiocytosis (HLH) are treated with a transplant from a donor. When no relative matches, that donor is often a stranger who joined a registry.
Join the registry
JBF points you to the official registry that serves your country. It explains who can join and what donation involves.
Help a family run a drive
If someone you love needs a donor, a registration drive can add many potential donors at once, for them and for others.
Support this work
Gifts to the Jada Bascom Foundation support donor-awareness education like this guide, community outreach, drive planning and referrals to official registries.
Sources and further reading
- Recommendations for the management of hemophagocytic lymphohistiocytosis in adults
Blood (American Society of Hematology) / Histiocyte Society working group, 2019-04-16 - Familial hemophagocytic lymphohistiocytosis
MedlinePlus Genetics, US National Library of Medicine, Accessed 2026-09-24
