NCCN Guidelines Published in 2021
The National Comprehensive Cancer Network® (NCCN®) – an alliance of leading cancer centers – announced the publication of new NCCN Guidelines® for histiocytosis. These clinical practice guidelines provide the latest evidence and expert-consensus for diagnosing and treating the three most common forms of histiocytosis in adults: Langerhans cell histiocytosis (LCH), Erdheim-Chester Disease (ECD,) and Rosai Dorfman Disease (RDD). Although the guidelines are focused on adult patients, there may be insight for pediatric physicians as well. The Guidelines are listed as “histiocytic neoplasms” and can be found on NCCN’s website.
You can find international expert consensus recommendations for the diagnosis and treatment of Langerhans cell histiocytosis in adults, here. You can download a copy, here. It is encouraged that you share this with your physicians for reference.
On November 1st, 2022, Memorial Sloan Kettering Cancer Center (MSK) announced that the U.S. Food and Drug Administration (FDA) has approved the oral MEK inhibitor drug cobimetinib (Cotellic®) for the treatment of adult patients with the family of blood diseases known as histiocytic neoplasms (HN). These diseases include Erdheim-Chester disease, Rosai-Dorfman disease, and Langerhans cell histiocytosis. Cobimetinib is an oral inhibitor of MEK1 and MEK2, currently approved to treat melanoma. Gratitude and congratulations to the Principal Investigator of this study, Dr. Eli Diamond, neuro-oncologist and neurologist at MSK and Chair of the Scientific Committee for the Histiocytosis Association. We applaud the efforts of Dr. Diamond and the entire study team for this tremendous advancement. Read more here.
The diagnosis of LCH is made following a biopsy of the affected tissue.
The diagnosis of LCH relies on the review of the biopsy of a tumor specimen under the microscope. In some cases, the classic findings of LCH may not be present or it might be difficult to obtain a tissue biopsy due to the location of the disease. In those instances, a diagnosis of LCH can still be made in the presence of characteristic clinical and radiographic features especially in conjunction with a mutation in the MAPK/ERK pathway. Some of the characteristic features of LCH include a) “punched out” bone lesions of the skull, jaw, spine, ribs, or hip bones and b) cysts or nodules in the upper part of the lungs in a smoker. A PET CT scan (head to toes) is the preferred imaging study as it also allows to search for other sites of disease more accurately as compared with other radiographic tests (see explanation of PET scan below).
A biopsy of one of the affected sites from LCH using a needle or through surgery is usually conducted and reviewed by an expert pathologist under the microscope for features suggestive of LCH. Often there are many other inflammatory cells mixed with the LCH cells in the biopsy specimen. A special test called an immunohistochemistry is undertaken by using stains (dyes) that check for certain markers (antigens) in the tumor sample. The stains are referred to as “positive” if the tumor cells bind to the dye and are visible under the microscope and referred to as “negative” if they do not. LCH cells are positive for the markers CD68, CD1a, and Langerin. In addition, testing for mutations of the BRAF and other genes through special tests called next generation sequencing (NGS) studies on the biopsy specimen or blood may be undertaken to help aid in the diagnosis or treatment. There are many laboratories that conduct NGS, and it is recommended to discuss with your doctor about which one to use for your case. (Learn more about these tests, here, toward the bottom of the page.)
In cases where the classic features under the microscope are not present (5% of the time), the presence of a mutation in combination with other features mentioned above may lead to a diagnosis of LCH.
Baseline Evaluation and Testing
Once the diagnosis of LCH is made, detailed history, physical examination, and specific tests are undertaken to determine the extent of the disease, i.e., determining what organs are involved with the disease and how severe. Below are descriptions of these baseline evaluations and tests.
- History: A detailed health history including onset and duration of symptoms, past illnesses, health and lifestyle habits, and medical conditions experienced by the patient and their family.
- Physical Examination: Includes a detailed exam of the body to search for signs of LCH. A specialized neurological exam may also be undertaken to evaluate if LCH has affected the brain and the nervous system, and includes testing for reflexes, coordination, and memory.
- Blood Tests:
- Complete blood count (CBC): to check for hemoglobin, platelets, and different types of white blood cells. (Hemoglobin is protein in your red blood cells that carries oxygen to your body’s organs and tissues and transports carbon dioxide from your organs and tissues back to your lungs. Platelets are clotting agents in cells. White blood cells are cells of the immune system that fight infections and diseases.)
- Blood chemistry tests: Studies for kidney, liver, coagulation, thyroid and immune function; abnormal level can be a sign of disease. Complete blood count, sedimentation rate, liver function tests, and electrolytes may be studied.
- C-reactive Protein (CRP): a marker of inflammation which can be elevated in LCH.
- Urine and Serum Osmolality / Water Deprivation Test: to check if the LCH has affected the pituitary gland hormone that helps to regulate the concentration of urine is being secreted accurately.
- Other hormone tests: to assess whether LCH has affected endocrine organs such as the pituitary gland, thyroid gland, or the adrenal glands.
- BRAF and other Gene Mutation testing: to check for gene mutations include BRAF-V600E and other mutations in the blood.
- Tests on the Biopsy Specimen:
- Immunochemistry: This test uses various types of dyes to find markers that can help in the diagnosis of LCH and differentiate it from other diseases. At times, BRAF-mutation testing can also be achieved relatively quickly using immunohistochemistry methods.
- Molecular Testing: This test involves testing the tissue for changes in the BRAF gene, especially the BRAF-V600E mutation, as well as other mutations that can be driving the LCH (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 diagnosis and treatment of LCH.
- 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. Sometimes, a high-resolution CT scan of the chest is conducted if there is suspicion of pulmonary (lung) LCH.
- Bone scan: This is a type of x-ray that looks for areas of tumor cells growing in the bones. A small amount of radioactive material is injected into a vein, collects in any abnormal parts of the bones, and is detected on a scanner.
- MRI (magnetic resonance imaging): A special type of scan that used magnetic waves to obtain detailed pictures of various body parts. A substance called gadolinium may be injected into a vein to get clearer pictures. Sometimes, a special MRI of the liver is conducted if there is suspicion of LCH involvement. This procedure is called magnetic resonance cholangiopancreatography (MRCP).
- Pulmonary Function Test (PFT): Also called a lung function test, it is a breathing test to evaluate the function of the lungs. This test measures the capacity of the lungs to hold air, inhale, exhale, and exchange oxygen with carbon dioxide in the air.
- Bronchoscopy: A procedure to look for abnormal areas inside the windpipe (trachea) and lung airways using a special camera called a bronchoscope. The bronchoscope is introduced through the mouth under sedation. This procedure can be used to obtain biopsy material.
- Endoscopic Retrograde Cholangiopancreatography (ERCP): When involvement of the digestive tract is suspected, this procedure can be used to diagnose and treat problems in the liver, gallbladder, bile ducts, and pancreas. ERCP combines the use of x-rays and a special tube with camera.
- Ultrasound: This is a procedure where sound waves are used to create echoes and collect pictures of organs.
- Electrocardiogram: This is a tracing of the heart rate and rhythm.
- Echocardiogram: This uses sounds waves to provide pictures of the heart in order to evaluate blood flow and heart function.
- 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.
- Specialist Examinations: This may include a neurological examination to test ability to walk, coordination, etc.; lung specialist evaluation if there is concern for pulmonary LCH; urinalysis to test the number of red cells, white cells, protein and sugar in the urine; other specialist visits or specific testing may be recommended by your physician (See Treatment section below).
If there are symptoms of diabetes insipidus, a water-deprivation test should be done. When the bones near the ears or eyes are involved, a head CT scan is indicated. An MRI of the brain may be necessary if the lesions are near the eyes or ears or there is suspicion of central nervous system (CNS) involvement. Chest CT and lung function studies are performed when indicated. Other testing may be done, depending on symptoms. Other biopsies may be performed if test results or abnormal findings during the physical exam cause the physician to suspect involvement of another area.
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 LCH. The severity of the disease is determined by how widespread the involvement occurs outside of bone and whether internal organs are affected.
Treatment
General Principles of Treatment
The treatment LCH often depends on the degree of organ involvement at diagnosis. In some patients who do not have any symptoms or any critical organ involvement like brain, liver, or spleen, it is reasonable to pursue a “watch and wait” strategy for some time without treatment. In these cases, close monitoring by a specialist is needed, and may include repeated imaging studies like PET scan or CT scan. Patients with LCH should have their treatment planned by a team of health care providers who are experts in the disease, including and not limited to the following:
- Cancer specialist (hematologist/oncologist)
- Hormone specialist (endocrinologist)
- Autoimmune disease specialist (rheumatologist)
- Lung specialist (pulmonologist)
- Brain and nervous system specialist (neurologist)
- Skin specialist (dermatologist)
- Ophthalmologist (Eye Specialist)
- Psychologist and supportive care specialist
Treatments Available for LCH
The treatment approach to has evolved significantly due to discovery of mutations in the BRAF and other genes, leading to the successful use of targeted therapies in most cases. Treatments for LCH can be divided into two categories: targeted and conventional treatments. Patients may also consider enrolling in a clinical trial if available near them.
Targeted Therapies
Targeted therapies include treatments that attack specific genes or protein in the cancer cells. These drugs have not been extensively used in LCH, and their use i typically reserved to situations where other conventional treatmen s ar unsuccessful or when LCH causes severe illness, and a quick response is needed. Targeted therapies are likely required to be taken for a long time, as there is concern that the LCH will recur upon stopping the drug. There are different types of targeted therapies available for LCH:
- BRAF-inhibitors (vemurafenib, dabrafenib, encorafenib): These drugs are typically used when there is presence of the BRAF-V600E mutation in the tumor cells. These drugs are taken by mouth and the dose can vary based on side effects and response to treatment. The common side effects include skin reactions (rash or skin cancer), joint pains, and fatigue. Seeing a skin doctor regularly can help with management of these effects. Other less common but important adverse effect is abnormal heart rhythm or reduced heart function. Some patients on these drugs will get routine electrocardiograms and echocardiograms to monitor the effects on the heart. Some of the side effects may necessitate switching from one type to BRAF-inhibitor to another.
- MEK-inhibitors (cobimetinib, trametinib, binimetinib): These drugs are typically used when there is no BRAF-V600E mutation in the tumor cells. These drugs are taken by mouth and the dose can vary based on side effects and response to treatment. Common side effects include skin rash, and patients may need to see a skin doctor for management. These drugs can also reduce the heart function, and sometimes an echocardiogram may be needed to monitor the effects on heart. Another notable side effect is changes in the layer of the tissue in the back of eye that senses light (retina) leading to blurry vision or loss of vision. It may be necessary to get regular eye exams while on treatment with these drugs.
There are several BRAF inhibitors (vemurafenib, dabrafenib, and encorafenib) and MEK inhibitors (cobimetinib, trametinib, binimetinib, selumetinib). The BRAF inhibitors are given for histiocytosis with the BRAFV600E mutation, and the MEK inhibitors are given in many different instances, including (1) cases of mutations in the MAPK pathway other than BRAFV600E (2) cases where no mutation has been identified and (3) for BRAFV600E mutations as well. In some instances of histiocytosis with BRAFV600E mutation, combined BRAF and MEK inhibitors are given. Which specific inhibitor medication (i.e. cobimetinib versus trametinib) a physician may administer can depend on several factors, such as (1) the amount of evidence that exists for a particular medication for a specific disease or age group (2) the experience of the physician administering a particular medication and (3) possible drug interactions between the inhibitor and an individual’s other medications.
Conventional Therapies
Conventional therapy is the therapy that is widely used and accepted by most healthcare professionals. There are different types of conventional therapies available for LCH:
- Chemotherapy (cladribine, cytarabine, hydroxyurea, vinblastine + prednisone, methotrexate + cytarabine): These drugs are given through the vein and are often the preferred treatment in cases with single-system multifocal disease, multi-system disease, or cases involving high-risk organs (brain, liver, spleen). Chemotherapy works by slowing the growth of or killing rapidly dividing tumor cells. These drugs have the potential to weaken the immune system and can lead to infectious complications. Vinblastine can cause damage to the nerves leading to neuropathy, manifesting as numbness, tingling, or pain of fingers and toes. Cladribine can increase the risk of a particular type of pneumonia (pneumocystis pneumonia) so preventative antibiotics may need to be administered alongside. Prednisone can lead to weight gain, stomach upset, sleep disturbances, and increased blood sugar. Methotrexate, when given through the vein in high dose, can lead to reduced kidney function or kidney failure. Methotrexate in combination with cytarabine can cause increased risk of infections and low blood cell count. Hydroxyurea can cause mouth sores, darkening of skin, rash, and rarely leg ulcers.
- Immunosuppressant and immunomodulator (thalidomide, lenalidomide, corticosteroids, low dose oral methotrexate): These are drugs given typically through mouth, except for corticosteroids, which can be given through injection or as a topical treatment (cream or lotion). These agents are often used in LCH involving the skin or bones. These drugs work by suppressing the immune system and reducing the inflammation induced by the tumor cells. Thalidomide and lenalidomide should not be taken by reproductive age women who are trying to get pregnant as it can cause severe birth defects in the child. Thalidomide can cause damage to the nerves leading to neuropathy, manifesting as numbness, tingling, or pain in fingers and toes. Thalidomide and lenalidomide can lead to increased risk of blood clots in the veins and can also decrease the production of blood cells. Corticosteroids when given through vein or mouth can lead to weight gain, stomach upset, sleep disturbances, and increased blood sugars. Oral low dose methotrexate can lead to stomach upset, mouth sores, liver damage, lung damage, and decreased production of blood cells.
- Other treatments (smoking cessation, surgery, radiation, zoledronic acid): Smoking cessation can lead to reversal of pulmonary LCH. Surgery may be used to remove LCH lesions from the bone, lymph node, or under the skin. Occasionally, radiation therapy using high energy x-rays or protons may be used to kill tumor cells, especially in the bone. The side effects of radiation can depend on the site of radiation and the amount of normal tissue exposed to the radiation. Zoledronic acid is given through the vein and can lead to shrinkage and reduced pain from bone lesions.
Treatment Approach in Adults with LCH
The treatment options for various forms of LCH are listed below:
- Unifocal (one location) LCH of the bone:
- Limited surgery called as curettage-can sometimes lead to complete response
- Radiation therapy
- Chemotherapy in case of large lesions or involvement of regions that are not easy to perform surgery on (skull, eye socket, hip bone, spine)
- Immunosuppressant or immunomodulator therapy
- Multifocal (more than one location) LCH of the bone:
- Radiation therapy for 2-3 spots
- Zoledronic acid
- Chemotherapy, single agent or combination
- Single-system Pulmonary LCH:
- Smoking cessation: quitting smoking in all forms (tobacco, marijuana, vaping). Sometimes this is the only treatment required and can lead to complete reversal of disease
- Corticosteroids can help with symptoms
- Chemotherapy, single agent or combination
- Targeted therapies
- Unifocal (one location) or multifocal (more than one location) Skin LCH:
- Observation (watch and wait) for asymptomatic disease
- Topical (cream or lotion) or injectable corticosteroid (hydrocortisone, triamcinolone)
- Thalidomide, lenalidomide, hydroxyurea, or low dose oral methotrexate
- Chemotherapy
- Multifocal and multi-system disease without critical organs (brain, spleen, liver, lungs):
- Chemotherapy, single agent, or combination
- Targeted therapies
- Radiation in some cases with limited spots of LCH
- Critcal organ involvement (brain, spleen, liver, lungs):
- Chemotherapy, single agent or combination
- Targeted therapies
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
- Hormone evaluation and treatment with the help of an endocrinologist
Treatment of Relapsed LCH
If LCH grows back after treatment, it is referred to as relapsed disease and if it does not respond to treatment at all, it is called as refractory disease. In such cases, one of the targeted or other conventional treatments than used previously may be 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.
Supportive Care
Despite improvement in treatments, several patients with LCH struggle with many symptoms such as extreme tiredness, body pain, depressed mood, anxiety, and memory difficulty. In many cases, getting additional input from psychology, supportive/palliative care, psychiatry, and pain specialists may be helpful. Leading a healthy lifestyle (exercise, balanced diet) may help improve some of these symptoms in addition to medications. Diabetes insipidus and other hormone deficiencies caused by LCH do not typically resolve despite successful treatment of LCH and patients need lifelong monitoring and hormone replacement. LCH survivors can also struggle with neurological problems from involvement of brain or spinal cord, or musculoskeletal issues from lesions of bones in the arms or legs. Children and young adults with pituitary involvement from LCH are at a high risk of developing neurodegenerative LCH later on in life (years to decades later), which manifests as difficulties with balance, behavior, and memory.
Prognosis
The prognosis of LCH has continued to improve with the introduction of newer treatments and early diagnosis. As patients with LCH live longer, they may be at a risk of other health problems from the treatments or as a process of getting older. People with LCH are also at a higher risk of other cancers than those without LCH. It is important for patients to continue to follow up with their healthcare provider to monitor for second cancers or side effects of treatment.