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Malignant Histiocytosis

Malignant histiocytosis (MH) is an ultra-rare subtype of histiocytic neoplasms, with estimated incidence of less than 1 case per million population. MH can affect children as well as adults, although it is more commonly seen among adult population.

Malignant histiocytosis (MH) is an ultra-rare subtype of histiocytic neoplasms, with estimated incidence of less than 1 case per million population. MH can affect children as well as adults, although it is more commonly seen among adult population. MH can occur by itself (primary MH) or in relation to another blood cancer like leukemia or lymphoma (secondary MH). MH encompasses 3 entities histiocytic sarcoma (HS), Langerhans cell sarcoma (LCS), and interdigitating dendritic cell sarcoma (IDCS); however, histiocytic sarcoma (HS) represents the vast majority of MH cases.

The average age at diagnosis is around 60 years, although malignant histiocytosis (MH) has been diagnosed in children as well as elderly. MH can involve any organ system of the body, with most common organs involved being lymph nodes, bone, lung, skin, bone marrow, and central nervous system. About a third of patients with MH present with single site of disease (unifocal MH) and the rest present with multiple sites (multifocal MH). The term “malignant” generally suggests aggressive disease, although there are several cases of unifocal MH that do not behave aggressively and have good outcomes.

Featured Articles:

Malignant Histiocytosis Comprises a Phenotypic Spectrum That Parallels the Lineage Differentiation of Monocytes, Macrophages, Dendritic Cells, and Langerhans Cells – ScienceDirect

Symptoms

Symptoms of malignant histiocytosis can vary depending on what type of histiocytoma you have. Symptoms may include:

  • A lump that grows larger
  • Pain
  • Numbness
  • Tingling
  • Swelling in your hand or foot
  • Fever
  • Loss of appetite

Diagnosis and Treatment

Diagnosis

The diagnosis of malignant histiocytosis (MH) relies on the review of the biopsy of a tumor specimen under the microscope by a pathologist. The pathologists usually conduct several tests on the sample, including dye testing (called as immunohistochemistry), to arrive at the diagnosis of MH and further classify its subtype. In some cases, the appearance of the cells is not classic for MH and additional consultations and testing may be necessary to ensure that the tumor is not related to another form of cancer. Often, the number of cells in biopsy specimens is not enough to run all the necessary tests, in which case a repeat biopsy can be recommended. In addition, testing for mutations of the BRAF and other genes through special tests called as next generation sequencing (NGS) studies on the biopsy specimen or blood may be undertaken to help aid in the diagnosis or treatment. In cases of MH arising after another blood cancer (secondary MH), the pathologist might order genetic testing to test whether the two cancers are related to each other and arising from the same parent cell type.

Workup

Once the diagnosis of MH is made, detailed history, physical exam, and tests are undertaken to determine the extent of the disease, i.e., determining what organs are involved with the disease:

  • History: A detailed health history is undertaken including the onset and duration of symptoms, past illnesses, health and lifestyle habits, and medical conditions experienced by the family.
  • Physical Examination: Includes a detailed exam of the body to search for signs of MH.
  • Blood Tests:
    • Complete blood count with differential: to check for hemoglobin, platelets, and different types of white blood cells.
    • Chemistries, including kidney and liver function tests: To evaluate the function of kidney and liver.
    • C-reactive protein (CRP)- a marker of inflammation which can be elevated in MH.
    • BRAF and other mutation testing- to check for BRAF-V600E and other mutations in the blood.
  • Tests on the Biopsy Specimen:
    • Immunohistochemistry: This test uses various types of dyes to find markers that can help in the diagnosis of MH and differentiate it from other diseases. At times, BRAF-mutation testing can also be achieved relatively quickly using immunohistochemistry methods.
    • Molecular testing for MAPK and other pathway mutations: This test involves testing the tissue mutations that can be driving the MH (BRAF, KRAS, NRAS, etc.). Some of these tests require sending the biopsy sample to a specialized laboratory that can take several days to weeks to result. Knowledge of these mutations can help with the treatment of MH.
    • PET (positron emission tomography) Scan: To check for tumor cells in the body, a small amount of radioactive sugar is injected into a vein followed by taking pictures in a PET-scanning machine. The disease-causing cells look brighter than surrounding cells due to increased uptake of glucose.
    • CT (computed tomography) Scan:This is an x-ray that takes a number of detailed pictures of various organs and structures within the body, often conducted in combination with a PET scan. Dye may be injected into a vein or taken by mouth to make the images clearer.
    • MRI (magnetic resonance imaging): A special type of scan that used magnetic waves to obtain detail pictures of various body parts. A substance called gadolinium may be injected into a vein to get clearer pictures. Sometimes, an MRI of the brain is conducted if there is suspicion of MH involvement.
    • Bone Marrow Aspiration and Biopsy: This procedure involves suctioning of a small amount of bone marrow and taking a small piece of the bone by inserting a hollow needle in the hip bone.

Staging

In many diseases or cancers, there is the concept of “staging” which refers to the extent or severity of the disease within the body (for example, “stage 4 lung cancer”). There is no standard staging system for MH. The severity of the disease is determined by how widespread the involvement is, including whether the disease is unifocal or multifocal.

Treatment of Primary Malignant Histiocytosis (MH)

Given the rarity of the disease, large studies examining treatments and outcomes are lacking, and treatment guidelines rely on individual reports of cases or expert opinion, borrowing from other histiocytic disorders. The treatment of MH often depends on the degree of organ involvement at diagnosis.

  1. Unifocal MH: For select cases of MH involving a single site that is easily removable/resectable by surgery (e.g., bone, skin, or lymph node), the outcomes can be very good by complete surgical resection. In some cases, a complete resection is not possible, and additional (adjuvant) radiation therapy is employed. Other cases that involve organs or sites where surgery is not considered safe or feasible are treated similar to multifocal MH.
  2. Multifocal MH: Patients with multifocal MH tend to have a more aggressive presentation and clinical course, with a lack of effective treatments. If a clinical trial is available, it is highly encouraged to enroll in one to try novel therapies. There is no established standard of care for multifocal MH, and treatments are adopted from other blood cancers, including histiocytic disorders like Erdheim-Chester disease and Langerhans cell histiocytosis. It is unknown at this time which of the treatments work best for cases with MH. Some of the treatments that have been utilized so far include the following:
    • Chemotherapy: Commonly used regimens for MH include combination chemotherapy drugs like ifosfamide, carboplatin, and etoposide (ICE) or Cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP). These treatments are typically administered in “cycles”, which each dose considered as 1 cycle, repeated up to 6 times every 3 weeks apart. Important side effects of these regimens includes lowering of blood cells (red blood cells, white blood cells, and platelets), risk of infections, kidney failure, and nerve damage. Other less studied chemotherapy drugs include vinblastine with prednisone, cladribine, or cytarabine as used in LCH.
    • Targeted therapy: Borrowing from ECD and LCH, targeted treatments like BRAF-inhibitors (vemurafenib, dabrafenib) or MEK-inhibitors (cobimetinib, trametinib) are sometimes utilized especially if there is a mutation in the MAPK pathway (BRAF, KRAS, MAP2K1, etc.). The effectiveness of such treatments for MH is currently unknown and available case reports suggest mixed results.
    • Other treatments: There are a handful of case reports of use of immunotherapy drugs (pembrolizumab and nivolumab), thalidomide, and alemtuzumab. The role of these therapies in MH treatment remains unclear.

Treatment of Secondary Malignant Histiocytosis (MH)

The optimal treatment for secondary MH, i.e., MH arising after a blood cancer such as leukemia or lymphoma, is unknown. In many such instances, MH occurs along with the other blood cancer, where the treatment is focused on the underlying lymphoma or leukemia. In other cases, if an active blood cancer other than MH is not found, such cases are treated similar to primary MH as described above.

Monitoring on Treatment

Once treatment is initiated,

patients need follow-up tests, or monitoring, for assessing the response to therapy and also management of side effects of treatments. Some of the tests that may be undertaken include:

  • Physical exam, including neurological exam.
  • Skin exams in patients on BRAF- and MEK-inhibitor treatments.
  • PET scan to check for reduced brightness and size of the tumor sites.
  • Additional imaging studies (CT, MRI) may be undertaken based on organs involved at diagnosis. Imaging (PET, CT, MRI) is usually repeated every few months and can be variable for each patient.
  • Blood tests to assess for changes from the disease or the treatments.

Treatment of Relapsed or Refractory Malignant Histiocytosis (MH)

If the MH grows back after treatment, it is called relapsed disease and if it does not respond to treatment at all, it is called refractory disease. In case of unifocal MH that recurs after initial surgery in a localized spot, a repeat surgery and/or radiation therapy can be considered. In some cases, a stem cell transplant from a donor (allogeneic transplant) is utilized as an aggressive treatment option if the patients respond to chemotherapy. In other cases, one of the targeted or other treatments than used previously are utilized. In some cases, a repeat biopsy of tumor cells may be needed for confirmation of diagnosis and mutation testing. If a clinical trial is available, that may be a consideration as well.

Prognosis

The prognosis of MH appears to be strongly tied to the extent of the disease and relationship to another blood cancer (primary vs. secondary MH). Many patients with unifocal MH who undergo complete surgical resection can have long-term remissions and often are cured of the MH. There are also very rare reports of unifocal MH undergoing spontaneous regression without treatment. Multifocal and secondary MH, on the other hand, generally tend to be associated with a poor prognosis, especially in cases with “aggressive presentation” leading to illness from rapid tumor growth.

FAQ

Please contact the Histiocytosis Association for support.

What Do I Do Now?

A new diagnosis of a histiocytic disorder can bring feelings of being overwhelmed, bewildered, scared, angry, sad, disappointed, helpless, and sometimes even feelings of guilt. It is a time filled with unknowns, change, and new people and situations. Most parents feel ill-equipped to understand what is happening to their child and how to navigate through the illness to recovery. There are, however, strategies and resources that can help you, your child, and other family members get through the uncertain times that lie ahead. One step at a time, you can gather information, create a support system, learn how to cope with stress, and become a strong advocate for your Histio Warrior as part of the medical team. The following tips and suggestions are provided to help guide you through this journey toward your Histio Warrior’s good health.

Histiocytosis can be considered a systemic illness; especially in cases where the disease is found in more than one system within the body. Some patients and caregivers may prefer to consult several specialists, depending on the different locations of symptoms. In this case, it is helpful to have one physician coordinate your care. An oncologist is usually the most appropriate choice.

Make sure that your doctor is someone you can trust and with whom you can communicate. Important qualities to look for in a doctor are:

  • feeling as though you are heard,
  • being given the opportunity to ask questions, and
  • feeling respected.

If you are unsure about your physician, it is reasonable to schedule another appointment to discuss your concerns. While it is ideal to find a physician experienced and knowledgeable about histiocytic disorders, it is not always possible to find one who is nearby. If this is the case, ask the physician if he/she is open to a consultation with a knowledgeable physician and is willing to learn more about the disease. The Histiocytosis Association maintains a listing of doctors in a Physician Finder who have are knowledgeable about histiocytosis. You may also call us at +1 856-589-6606 for help finding other physicians in your area or for more information.

Call your insurance company to find out whether your plan will cover visits to the physician you are considering. Oftentimes a Team Social Worker and/or the hospital financial counselor can help smooth out insurance problems. Ask for help from a trusted friend if you feel overwhelmed in dealing with insurance issues.

Talking with your child: If your child is old enough to understand, sharing information can help him/her build trust in both you and his/her/your medical caregivers. It can also help your child cooperate with treatment and become a part of his/her/your medical team.

  1. Use words and ideas that are appropriate for your child’s age.
  2. Share information at a level that is in keeping with his/her ability to understand.
  3. Use your child’s questions as a guide to what he/she wants to know.
  4. Encourage your child to talk about his/her fears and concerns.
  5. Remind your child how much you love him/her.

If you are uncertain about how to talk to your child, your healthcare team can be of assistance.

Talking with family and friends: In the days and weeks following diagnosis, extended family and friends will need to be notified and periodically updated. However, explaining your situation multiple times can be exhausting and time-consuming. The Association offers a private Facebook group to help connect you with others. Some patients and families find that journaling is therapeutic and can provide an easy way to track their history and progress.

Talking with your child’s siblings: When your child is diagnosed with a histiocytic disorder, everyone in the family is affected, including brothers and sisters. They may feel anxious, lonely, resentful about the attention their sibling is getting, guilty about being healthy, or even responsible for the illness.

  1. Give information that is appropriate for your child’s age.
  2. Explain that no one did anything to cause the illness, and reassure them that it is not contagious.
  3. Give them a chance to talk about how the illness is affecting them or you. Be willing to answer questions.
  4. Remember that it will be easy for them to feel overlooked and unimportant, so it will be important to show that you love them and are proud of them.

Talking with your child’s school: Contact your school principal/counselor regarding your child’s diagnosis or if your diagnosis may affect your child. You may want to take brochures and other basic information about your histiocytic disorder. If your child is the patient, provide a written description of the health needs, such as what medications may need to be given at school, dosages, and times, signed by your physician. (Some schools will provide the form to be filled out and signed by your child’s physician.) Ask for a plan to take care of your child’s needs at school. You may need to provide written permission for the school to communicate with your physician, in case of an emergency.

Appointments: A calendar is a useful tool for remembering appointments and planning for changes to your established schedule. Calendars that show a week at a time also provide room on each day to record additional brief notes and reminders.

Medical Information: While some basic medical notes can be kept in a calendar, some patients and parents may choose to enter medical information in a laptop or keep a separate notebook. Be sure to date all entries. This information will be especially helpful when a new or different caregiver is involved. Examples that you may want to keep track of include:

  1. Results of various tests.
  2. A listing of allergies.
  3. A listing of medications and dosages.
  4. Names and phone numbers of your medical care team.
  5. Health information, such as your hospital number, social security number, and insurance information.
  6. Records of what was discussed during a medical visit/phone conversation and by whom.
  7. Notation of changing symptoms.

Adults may find it helpful to collect and organize medical records, starting as soon as possible after diagnosis. Although the original reports must remain in the physician or hospital file, you are legally entitled to copies of your records. You must submit a signed request for each physician’s office and the hospital. By keeping all records in one place, you can easily share these with other health care providers that you may see in the future. Follow this link to read more about obtaining your medical records.

If you have health insurance, it’s important that you know what your plan covers. Read your policy carefully to understand the health and medical services covered. Find out the portion of medical expenses you’ll be responsible for paying. When you have questions or there are things you don’t understand, reach out to other experts available to you, such as the human resources personnel at your place of employment or financial counselors at your medical treatment center. If filing and tracking claims feels overwhelming, you may want to ask a trusted friend or relative to assist in managing your insurance issues.

When you call the insurance company, ask to work with one case manager. This may help simplify the process by having one person that knows your needs and can manage your claims. If possible, communicate with the same person on an ongoing basis. Remember to keep a journal of all encounters.

If you don’t have health insurance, if coverage is not adequate, or if you are not able to get insurance because of your pre-existing condition, you may qualify for your state’s high-risk insurance pool. You can obtain more information about whether your state participates at the National Association of State Comprehensive Health Insurance Plans website. If your state does not participate, you may qualify for the federal high-risk insurance pool. For more information, contact the U.S. Department of Health and Human Services.

Online: You can subscribe for our emails and you will receive important announcements regarding the latest information on the histiocytic disorders. The Association also maintains a Facebook page for families and patients with this disease.

Local support: The hospital where you or your child is being treated may have a support group for patients or parents of children with histiocytic disorders, rare diseases in general, or even cancer. Establishing face-to-face relationships with others going through similar experiences can be helpful.

The Association sponsors patient and family Regional meetings, which are held in various locations around the U.S. and hosted by Association staff and volunteers. They are a good opportunity to meet other families and patients, learn from expert physicians, receive and give emotional support, and share practical coping skills while also providing a time to relax, knowing you are with people who understand.

Fundraising events for histiocytic disorders are another way to make connections with families in your region. A listing of dates and fundraising events is provided on the Upcoming Events page.

Virtual opportunities to connect are also available.

Self-education about histiocytic disorders is an important part of advocating for your and your child. It will help you to make informed decisions about care and play a more active role in recovery.

The Association website provides education on a number of topics, including disease information, family resources, and past and ongoing research projects. The Histio Resource Directory provides an extensive listing of global, national, and state-by-state resources for patients and families. Some of the resources listed are informational, while others are service-based. A listing of past and current research projects funded by the Association can be found on the Grant Awards page, providing a glimpse into the past trends and current progress of research into the histiocytic disorders. The Disease Information section of the website features detailed, reliable information on all of the histiocytic disorders. This can be printed out and shared with medical caregivers, family, and friends if needed.

The Internet is a good source of information about histiocytosis and the treatment options, but the amount of information can be overwhelming, and the information is not always reliable. Some of it, in fact, is inaccurate. Reliable information is more likely to be found in more current documents that are free of grammatical and spelling errors, appear to be objective, are free of advertisements, and clearly state their sources.

It is essential to take an active role in your or your child’s health care. However, many patients and caregivers have little experience being advocates when they first receive a rare disease diagnosis. The following is a list of essential tips for becoming a successful advocate:

  1. Learn about the diagnosed type of histiocytosis and become acquainted with the basic medical terms. Knowledge is empowerment.
  2. Know the warning signs that mean you may need emergency help.
  3. Know who to call in case of an emergency, and keep phone numbers handy.
  4. Keep a list of healthcare members involved in your medical care, along with contact information.
  5. If possible, take a companion (family member or friend) along on important medical appointments. The companion can help with remembering details of what was said and may assist by taking notes.
  6. Write down your questions before entering appointments or meetings and write down further questions as you think of them during the meeting. Don’t be afraid to ask these questions. This will be an important step in beginning to understand more about the disease. Medical information is often confusing and the language used by medical professionals is not easily understood, especially during stress. Whenever someone uses a word that you don’t understand, stop the conversation for a minute and ask the person to explain.
  7. Keep a healthcare notebook with a listing of allergies, medications, symptoms, and communications with healthcare providers.
  8. Find out about resources that the hospital provides, such as a social worker or patient representative. They can often assist with transportation costs, temporary housing if needed, parking fees, insurance issues, counseling, and other services.
  9. Be persistent in getting the care you feel that you or your child needs. Don’t hesitate to ask for what you need, and if you do not feel responded to, ask again or ask someone who will respond.

Trust your intuition. It can be a powerful decision-making tool. You know yourself or your child better than anyone else.

Being sick or caring for a sick child/loved one can be stressful and may take a toll on your physical and emotional health. Recognizing your own needs for support, help, health, and comfort can be difficult when you’re focused on the needs of others, but it’s important to remember that caring for yourself is essential. When your needs are taken care of, your loved ones will also benefit. Give yourself time for regular physical activity and rest. Pay attention to signs of stress, and consult your physician if you need further help.

Printable Fact Sheets

Learn more about the different types of histiocytic disorders from these helpful fact sheets. Printing these for family and friends is a quick and easy way to teach them about the disease.

Choose from the following Fact Sheets:

Histiocytic Disorders Overall FAQ

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.

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.

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.

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.

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.

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