What is Acquired Hemophagocytic Lymphohistiocytosis (HLH)?
Acquired hemophagocytic lymphohistiocytosis (HLH) is a rare condition that causes the immune system to become dangerously overactive. Instead of protecting the body normally, immune cells begin attacking healthy blood cells and tissues.
This condition can affect adults and children, but acquired HLH is usually linked to another medical problem such as an infection, cancer, or autoimmune disease. The inflammation caused by HLH can affect several organs, especially the liver and spleen.
Acquired HLH may be triggered by:
- Viral infections such as Epstein-Barr virus (EBV)
- Bacterial or fungal infections
- Blood cancers like lymphoma or leukemia
- Autoimmune diseases
- Medicines that weaken the immune system
Symptoms
Symptoms of acquired HLH can develop quickly and may become severe without treatment. Many symptoms are caused by widespread inflammation throughout the body.
Common symptoms may include:
- Persistent fever
- Enlarged spleen or liver
- Extreme tiredness or weakness
- Swollen lymph nodes
- Skin rash
- Yellowing of the skin or eyes (jaundice)
- Easy bruising or bleeding
- Cough or trouble breathing
- Abdominal pain
- Nausea, vomiting, or diarrhea
- Headaches or confusion
- Trouble with balance, walking, or vision
How is it diagnosed?
Because HLH shares symptoms with many other illnesses, diagnosis often involves several tests. Your provider will review your symptoms, medical history, and perform a physical exam.
Testing may include:
- Blood tests to check blood cell levels and inflammation
- Ferritin and triglyceride testing
- Infection screening
- Imaging studies to look for enlarged organs
- Bone marrow biopsy to examine blood-forming cells
- Genetic testing in certain situations
Early diagnosis is important because HLH can worsen quickly.
How is it treated?
Treatment focuses on controlling the overactive immune response and treating the condition causing HLH.
Treatment options may include:
- Steroids to reduce inflammation
- Medicines that suppress or regulate the immune system
- Chemotherapy medicines in severe cases
- Antibiotics, antivirals, or antifungal medications when infection is involved
- Supportive care in the hospital
Some people improve once the underlying illness is treated. Others may need more advanced treatment, including a stem cell transplant if the disease does not respond to medicine.
Recovery depends on how severe the condition is and how early treatment begins. Ongoing follow-up care is often needed.
