Frequently Asked Questions

Juvenile xanthogranuloma (JXG)

The questions below are regarding Juvenile xanthogranuloma (JXG) specifically. Please click on a question to view the answer.

  1. What causes juvenile xanthogranuloma (JXG)?
  2. Is there a cure for JXG?
  3. What are the different therapies/treatments commonly used to treat JXG?
  4. Can an infant be tested at birth for JXG?

Histiocytic Disorders and Orphan Diseases

The questions below are regarding Histiocytic Disorders and Orphan Diseases in general. Please click on a question to view the answer.

  1. What are histiocytic disorders, and how are they classified?
  2. Why are all of these diseases with different names considered to be related to each other?
  3. Where can I find reliable information about histiocytosis?
  4. How can I explain histiocytosis to family and friends?
  5. What is an orphan disease?
  6. How many orphan diseases are there?
  7. Where can I learn more about rare diseases in general?

Juvenile xanthogranuloma (JXG)

  1. What causes juvenile xanthogranuloma (JXG)?
    JXG involves the over-production of a kind of histiocyte called a dendritic cell. What triggers these cells to accumulate is not known.

  2. Is there a cure for JXG?
    We usually don’t use the term “cure” with this disease, although most patients with only skin or soft tissue JXG have spontaneous remission over time without treatment. Children with liver, bone marrow, CNS involvement and masses in the abdominal cavity usually survive with chemotherapy treatment. There is no established period of inactive disease before JXG is considered cured.

  3. What are the different therapies/treatments commonly used to treat JXG?
    Patients with a single lesion or just a few lesions, as well as children with skin-only JXG often require no therapy. Surgical removal may be required if the mass is causing organ dysfunction. A small percentage of patients with rapidly growing disease may require treatment with chemotherapy or low-dose radiation, however there is no standard of therapy that has been agreed upon. Steroids have been used to treat eye lesions and in some cases low dose radiation has been effective in preventing visual loss.

  4. Can an infant be tested at birth for JXG?
    A biopsy of the affected tissue, rather than a blood test, is required for diagnosis and would therefore not be appropriate as a routine test unless this disease is suspected.

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Histiocytic Disorders and Orphan Diseases

 

  1. What are histiocytic disorders, and how are they classified?
    Histiocytic disorders are a diverse group of diseases caused by over-production of white blood cells known as histiocytes, which can lead to organ damage and tumor formation. They include a wide variety of conditions that can affect both children and adults.

    The disorders are classified into three groups based on the types of histiocyte cells involved.
    • The first group is called a dendritic cell disorder, and the most common disease in this group is Langerhans cell histiocytosis. Also included in this group are more rare diseases, juvenile xanthogranuloma (JXG) and Erdheim Chester.
    • The second group is called a macrophage cell disorder, and includes primarily hemophagocytic lymphohistiocytosis (HLH) and Rosai-Dorfman.
    • The third group is called malignant histiocytosis and includes certain kinds of leukemia and tumors.
  2. Why are all of these diseases with different names considered to be related to each other?
    All of the diseases are caused by the over-production of white blood cells called histiocytes. Their different classifications depend on the type of histiocyte involved.

  3. Where can I find reliable information about histiocytosis?
    The Histiocytosis Association’s online community provides a number of informational documents and articles, as well as links to medical articles about the histiocytic disorders. While the Internet does provide a significant volume of information about histiocytic disorders, some of this information is not accurate. It is important to look for documents that are current, are free of grammatical and spelling errors, appear to be objective, are free of advertisements, and clearly state their sources.

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  4. How can I explain histiocytosis to family and friends?
    Histiocytosis is a rare disease that is caused by the over-production of a type of white cell that can lead to organ damage and the formation of tumors. The Histiocytosis Association’s Disease Fact Sheets are also a great way to help explain these complicated diseases to family and friends.

  5. What is an orphan disease?
    According to the Rare Disease Act of 2002, an orphan disease, also known as a rare disease, affects less than 200,000 persons in the U.S., or less than 1 in 1500 people. The criteria may vary in other countries. For example in Europe, an orphan disease is defined to occur in less than 1 in 2000.

  6. How many orphan diseases are there?
    According to the National Institutes of Health there are approximately 6800 such diseases. Combined, they affect nearly 30 million Americans.

  7. Where can I learn more about rare diseases in general?

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