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At Children’s Mercy, we specialize in diagnosing and treating rare childhood diseases — including histiocytosis. Whether your child has just been diagnosed or you’re searching for answers, our team of pediatric experts will work closely with your family to create a personalized care plan that meets your child’s unique needs.

We’re proud to be one of the few centers in the nation with the expertise and resources to care for children with all forms of histiocytosis, and we’re here to guide your family every step of the way.

What is Histiocytosis 


Histiocytosis is a rare group of diseases that happen when the body makes too many histiocytes—a type of white blood cell that normally helps fight infection. When these cells build up in the body, they can cause inflammation and damage to organs and tissues.

There are several types of histiocytosis, and each one can affect children differently:

  • Langerhans Cell Histiocytosis (LCH):This is the most common type. It can cause skin rashes, bone pain, or even affect the lungs and other organs.
  • Hemophagocytic Lymphohistiocytosis (HLH):A more aggressive form that can cause fever, enlarged organs, and serious inflammation throughout the body.
  • Sinus Histiocytosis with Massive Lymphadenopathy:A rare condition that causes swollen lymph nodes, often in the neck.
  • Juvenile Xanthogranuloma:A benign lump or bump caused by a buildup of immune cells, that usually goes away on its own over time.

What Causes It?


In many cases, the exact cause is unknown. Some forms may be linked to genetic changes or problems with the immune system.

How is it Treated?


Treatment depends on the type and severity of the disease. It may include:

  • Steroids or chemotherapy to reduce inflammation
  • Targeted therapies for specific genetic mutations
  • Supportive care to manage symptoms

What to Expect 


We understand that a diagnosis of histiocytosis can feel overwhelming. Our goal is to support your family every step of the way — from the first appointment to long-term follow-up care.

Your First Visit


During your first visit, you’ll meet with a team of pediatric specialists, including hematologists/ oncologists, nurse practitioners and social workers. We’ll review your child’s medical history, perform a physical exam, and may order tests such as:

  • Blood work
  • Imaging (like X-rays or MRI)
  • Biopsy (if needed)

We’ll explain everything clearly and answer all your questions.

Personalized Treatment Plan


Once we have a diagnosis, we’ll create a treatment plan tailored to your child’s specific type of histiocytosis. This may include:

  • Medications (such as steroids or chemotherapy)
  • Targeted therapies, including collaboration with pediatric specialists like orthopedic surgeons, endocrinologists, dermatologists or pathologists.
  • Supportive care (pain management, nutrition, etc.)

Ongoing Care and Monitoring


Treatment may take place over weeks or months, depending on the type and severity of the disease. We’ll schedule regular follow-ups to monitor progress and adjust the plan as needed.

You’ll also have access to:

  • Child life specialists to support emotional wellbeing
  • Social workers and financial counselors
  • Educational resources to help your child stay on track

Frequently asked questions 

The exact cause isn’t always known. Some types may be linked to changes in the immune system or specific genetic mutations. It’s important to know that it’s not contagious and not caused by anything a parent did or didn’t do.

Some forms of histiocytosis, like Langerhans Cell Histiocytosis (LCH), behave like cancer and are treated with similar medications. Others, like Hemophagocytic Lymphohistiocytosis (HLH), are considered immune system disorders. Your child’s care team will explain the specific type and treatment approach.  

Symptoms vary depending on the type and where it affects the body. Common signs include:

  • Skin rashes

  • Bone pain or swelling

  • Fever

  • Enlarged liver or spleen

  • Fatigue or irritability

Diagnosis may involve:

  • Blood tests

  • Imaging (like X-rays or MRIs)

  • Biopsies (removing a small sample of tissue for testing)

Our team uses these tools to understand the type and severity of the disease.

Some children may need to stay in the hospital for treatment or monitoring, especially early on. Others can receive care through outpatient visits. Your care team will explain what’s best for your child’s situation.  

Many children respond well to treatment, especially when diagnosed early. Some may need long-term follow-up to monitor for recurrence or late effects. Our team will be with you throughout your child’s journey.

Areas of research focus


Our team is working on a HLH-prospective study looking at cytokine levels in the Pediatric Intensive Care Unit, collaborating with Allergy/Immunology and Critical Care Medicine.

Each year, the Division of Pediatric Hematology, Oncology and Bone Marrow Transplantation at Children’s Mercy Kansas City provides comprehensive care to nearly 2,000 children with childhood cancers, sickle cell disease, hemophilia and other blood disorders, with survival rates frequently above national averages. 

Our commitment to clinical research and innovation has helped us earn recognition as one of the top cancer programs for kids in the nation by U.S. News and World Report. Children’s Mercy also has received accreditation from the American College of Surgeons Commission on Cancer and the Foundation for Accreditation of Cellular Therapy.