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.


What to Expect

If your child has been diagnosed with HLH, we want you to know that you are not alone – the Center for Rare Disease Therapy is here to help.

Our specialists have the expertise and experience to treat HLH across the spectrum of severity and in children of all ages. Because our doctors work as a team, your child can be seen by all of the specialists he or she needs in one visit. These may include specialists in the immune system, blood diseases, bone marrow or liver transplantation, genetic counseling, and child development.

We understand that the whole family is affected when a child has a rare disease. We see each family as our partner in caring for their child. We think the best approach to caring for a child with a rare disease emerges when we combine our depth of experience in rare diseases with your expertise in what’s best for your child.

We will talk with you about what we think is likely to happen with your child in the near future and about options we can suggest for treating and caring for your child. If surgery is an option for your child, we will help you understand what the surgery entails and what you may need to do to prepare for it. We will also talk with you about what you can do at home to care for your child and improve his or her quality of life. Please feel free to ask our specialists any questions you have about your child’s disease, treating and caring for your child, or anything else that is on your mind.

How long might we have to wait for test results?

If the doctors order tests, you can expect to receive a phone call within 2 weeks to explain the results and discuss recommended next steps. Test results are also made available on Children's patient portal, myCHP, which is provided at no cost to patients, parents, and guardians.

To make an appointment with one of our specialists for your child with HLH, please call Jodie Vento at 412-692-7273 or send an email to rarecare@chp.edu.


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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 Children’s Hospital of Pittsburgh of UPMC for a child diagnosed with HLH, please contact:

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

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