What Is Hemophagocytic Lymphohistiocytosis (HLH)?

Hemophagocytic lymphohistiocytosis (HLH) is an inherited disease of the immune system. It's known as a "primary immunodeficiency."

The body's immune system fights off infections and anything else it sees as foreign invaders to the body.

In HLH, the body makes too many immune cells. These immune cells see the body's internal organs as invaders.

The cells attack organs including the:

  • Liver
  • Brain
  • Bone marrow

HLH is a rare disease that affects about one in 50,000 births.

What Causes HLH?

Children inherit this disease from their parents, and changes to different genes can cause subtypes of HLH.

Some types of HLH do not have a genetic cause, but the effect on the body is the same.

Hemophagocytic Lymphohistiocytosis Symptoms

HLH symptoms often appear within the first few months or years of birth.

Symptoms of HLH are much the same as those of other childhood illnesses, making it hard to diagnose.

Some symptoms are:

  • Enlarged lymph nodes
  • Skin rashes
  • Fever
  • Jaundice (yellowing of the skin and eyes)
  • Enlarged spleen
  • Breathing problems
  • Easy bruising

Complications of HLH disease

HLH causes the overactive immune system to attack the body, causing organ damage.

Children with this disease can have nervous system problems, spleen enlargement, and liver and lung damage.

If HLH is causing nervous system problems in your child, you may notice symptoms such as:

  • Irritability
  • Tiredness or fatigue
  • Abnormal muscle tone
  • Seizures

Diagnosing HLH Disease

After talking to you about your child's medical history and symptoms, your doctor will use a blood test to help diagnose HLH.

If results come back positive for HLH, your child might need further blood tests to include genetic testing. Genetic blood tests help doctors learn which genetic mutation is causing the disease, or if there's no genetic cause.

HLH Treatment

The goal of treating HLH is to stop the immune system from attacking the body's organs. This disease needs treatment quickly, because of how fast it progresses.

Treatment may include medicines that suppress the immune system, to control the damage it's doing to the body.

Treatments for HLH may include:

  • Chemotherapy
  • Steroids
  • Antibody therapy

Some cases of HLH — mostly the type that's not genetic — go away after treatment and won't need further care.

If medicine doesn't resolve your child's genetic HLH, talk to your doctor about other treatment options. Ask if your child might benefit from a bone marrow or cord blood transplant to cure the disease.

Bone marrow transplant to treat HLH

Before a bone marrow transplant, your child receives chemo to destroy the immune system. Surgeons then transplant healthy bone marrow into your child.

If your child also has severe lung damage, surgeons might also perform a lung transplant at this time.

The Hillman Center for Pediatric Transplant has the only program in the world that offers tandem lung and bone marrow transplantation.

We also pioneered a reduced-intensity bone marrow transplant program. The program helps reduce the negative effects a bone marrow or stem cell transplant has on the body's organs.

Because transplants are high-risk treatments, your child may need to take medicine for his or her entire life.


Paul Szabolcs, MD

Chief, Bone Marrow Transplantation and Cellular Therapies

Dr. Szabolcs is a pioneer in reduced-toxicity/intensity unrelated donor cord blood transplant for inborn immunity errors. He's the first to prove the usefulness of sequential lung and bone marrow transplantation from the same unrelated deceased donor.


Your Child's HLH Consult and Care: What to Expect

If a doctor diagnosed your child with hemophagocytic lymphohistiocytosis, we want you to know you're not alone. The Center for Rare Disease Therapy is here to help.

To make an appointment for your child or refer a patient for HLH care, contact us by:

Here’s what you can expect when you come to us for your child's HLH consult and care.

How soon can I get an appointment for my child's hemophagocytic lymphohistiocytosis?

In most cases, we can see a new patient within 1 to 2 weeks.

We'll ask the referring doctor to send your child's medical records so we can go through them before your visit.

What should I expect at my child's first visit for HLH?

You can expect your first visit to take from 4 to 6 hours.

Your child will have a complete assessment. The doctor will make or confirm a hemophagocytic lymphohistiocytosis diagnosis and find out how much the disease has progressed.

Because we work as a team here at the center, other experts might see your child during your visit.

These may include specialists in:

  • Immune system diseases
  • Blood diseases
  • Bone marrow or liver transplantation
  • Genetic counseling
  • Child development

What happens next after my child's visit to the Center for Rare Disease Therapy?

Members of your child's HLH care team will talk with you about next steps, such as:

  • Options for treating hemophagocytic lymphohistiocytosis.
  • Ways to care for your child at home to help improve his or her quality of life.

If surgery might be a treatment option for your child's HLH, we'll discuss all the details. We'll let you know how you and your child can prepare.

By the end of your visit, you'll have a care plan tailored to your child’s HLH disease and health needs. We'll also schedule a follow-up visit in 3 months.

You'll meet our nurse practitioner (NP). If you have any questions or concerns before your next appointment, you can contact our NP by phone or video conference.

Before you leave, please feel free to ask us about your child's HLH diagnosis, treatment, or anything else on your mind.

How long will I need to wait for my child's HLH test results?

We will call within 2 weeks to discuss the test results and next steps for your child's HLH care.

You can also find your child's test results if you signed up for myCHP — Children's patient portal.

myCHP lets you manage your child's health online. It's free to patients, parents, and guardians of UPMC Children's Hospital of Pittsburgh.

Partners in Your Child's HLH Care

When a child has a rare disease like hemophagocytic lymphohistiocytosis, it affects the whole family.

At the Center for Rare Disease Therapy, we see each family member as our partners.

The best care approach happens when we merge our HLH expertise with your knowledge of what’s best for your child.

Contact us to learn more about HLH or make an appointment for your child:


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Learn how families are finding help and hope at the Center for Rare Disease Therapy at Children’s Hospital of Pittsburgh of UPMC.

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Contact Us

At the Center for Rare Disease Therapy, every child diagnosed with a rare disease receives an individualized treatment plan and family-centered care.

For an appointment, consultation, or patient referral with an expert at UPMC Children’s Hospital of Pittsburgh for a child diagnosed with HLH, please contact:

Jodie Vento, MGC, LCGC
Phone: 412-692-7273
Email: rarecare@chp.edu

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