National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Mastocytosis

Mastocytosis occurs when too many mast cells accumulate in the skin and/or internal organs such as the liver, spleen, bone marrow, and small intestines. Mast cells are a type of white blood cell in the immune system. Mast cells are responsible for protecting the body from infection and releasing chemicals to create inflammatory responses.[1] The signs and symptoms of mastocytosis vary based on which parts of the body are affected. There are two main forms of mastocytosis. Cutaneous mastocytosis only affects the skin and is more common in children. Systemic mastocytosis affects more than one part of the body and is more common in adults.[1][2]  

Mastocytosis is usually caused by changes (known as variations or mutations) in the KIT  gene. Most cases are caused by somatic mutations, meaning they only occur in certain parts of the body and are not inherited or passed on to the next generation. However, mastocystosis can rarely affect more than one person in a family.[1][3][4] Mastocysotis may be suspected when a doctor sees a person has signs and symptoms of the disease. Diagnosis may be confirmed with a skin biopsy or bone marrow biopsy.[2] Treatment of mastocytosis is based on the signs and symptoms present in each person and can include antihistamines, mast cell stabilizers, corticosteroids, and oral psoralen plus UV-A therapy.[2] 
Last updated: 2/22/2018
The signs and symptoms of mastocytosis vary based on which parts of the body are affected. Signs and symptoms of mastocytosis are more likely to occur after a “trigger” such as a change in temperature, certain medications, emotional stress, or irritation of the skin.[2] There are two main forms of mastocytosis:[1]
  • Cutaneous mastocytosis:  This form only affects the skin. The most common signs and symptoms include small tan-red macules that develop on the body, especially on the upper and lower extremities and on the thorax and abdomen. Another common feature  is known as Darier’s sign, which is the development of lesions in a new area shortly after irritation to the skin such as scratching. When cutaneous mastocytosis occurs in children, signs and symptoms tend to improve or go away completely by the time the child reaches puberty.
  • Systemic mastocytosis:  This form affects more than one part of the body such as the bone marrow, liver, and GI system. Signs and symptoms may include the skin findings associated with cutaneous mastocytosis, as well as symptoms such as low blood pressure (hypotension) abdominal pain, vomiting, diarrhea, fatigue, and frequent headaches. These symptoms may be episodic, meaning they only occur once in a while, or chronic, meaning symptoms are present during a long time. People with systemic mastocytosis may also present to the doctor with an enlarged liver and spleen (hepatosplenomegaly), anemia, or osteoporosis.
Many people affected by mastocytosis, especially systemic mastocytosis, also have symptoms of anxiety and depression. It is unknown if this is due to the stress of having these symptoms as part of daily life, or if the accumulation of mast cells may also affect the chemicals in a person’s brain, causing anxiety and depression.[1] 
Last updated: 2/22/2018

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Showing of 33 |
Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Abnormality of skin pigmentation
Abnormal pigmentation
Abnormal skin color
Abnormal skin pigmentation
Abnormality of pigmentation
Pigmentary changes
Pigmentary skin changes
Pigmentation anomaly
[ more ] 		0001000
Macule
Flat, discolored area of skin
0012733
Mastocytosis 0100495
Pruritus
Itching
Itchy skin
Skin itching
[ more ] 		0000989
Urticaria
Hives
0001025
30%-79% of people have these symptoms
Abnormal blistering of the skin
Blistering, generalized
Blisters
[ more ] 		0008066
Diarrhea
Watery stool
0002014
Impaired temperature sensation
Abnormality of temperature sensation
Loss of temperature sensation
[ more ] 		0010829
Nausea and vomiting 0002017
5%-29% of people have these symptoms
Acute leukemia 0002488
Angioedema 0100665
Anorexia 0002039
Arrhythmia
Abnormal heart rate
Heart rhythm disorders
Irregular heart beat
Irregular heartbeat
[ more ] 		0011675
Asthma 0002099
Chronic leukemia 0005558
Cough
Coughing
0012735
Fatigue
Tired
Tiredness
[ more ] 		0012378
Gastrointestinal hemorrhage
Gastrointestinal bleeding
0002239
Hepatomegaly
Enlarged liver
0002240
Hypercalcemia
High blood calcium levels
Increased calcium in blood
[ more ] 		0003072
Hypotension
Low blood pressure
0002615
Osteoporosis 0000939
Recurrent fractures
Increased fracture rate
Increased fractures
Multiple fractures
Multiple spontaneous fractures
Varying degree of multiple fractures
[ more ] 		0002757
Respiratory insufficiency
Respiratory impairment
0002093
Sarcoma
Cancer of connective tissue
Malignant connective tissue tumor
[ more ] 		0100242
Splenomegaly
Increased spleen size
0001744
Telangiectasia of the skin 0100585
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance 0000006
Cutaneous mastocytosis 0200151
Edema
Fluid retention
Water retention
[ more ] 		0000969
Erythema 0010783
Hypermelanotic macule
Hyperpigmented spots
0001034
Telangiectasia macularis eruptiva perstans 0007583
Showing of 33 |
Last updated: 7/1/2020
Most cases of mastocytosis are caused by a change (known as variation or mutation) in the KIT gene. This gene provides instructions to the body to make a protein that helps control many important cellular processes such as cell growth and division, survival, and movement. This protein is also important for the development of certain types of cells, including mast cells. Mast cells are cells of the immune system that protect the body against infections and produce an inflammatory response when it senses that the body is being attacked.[2] 

Mutations in the KIT gene can lead to an overproduction of mast cells. In mastocytosis, mast cells accumulate in the skin and/or internal organs, leading to the many signs and symptoms of the disease.[1] 
Last updated: 2/22/2018
Most cases of mastocytosis are not inherited. The change (variation or mutation) in the KIT gene that causes many cases of mastocytosis is typically a somatic mutation. Somatic mutations occur after the egg and sperm join (conception) and are only present in certain cells of the body. Typically, affected cells do not include the egg and sperm (germ cells). Therefore, the genetic change associated with mastocytosis typically only occurs in one person in a family, and the disease is not passed on to the next generation.[2]

Mastocytosis can rarely affect more than one person in the same family. This is known as familial mastocytosis and occurs when a person does have the KIT mutation in the egg or sperm (germ cells). In these cases, the mastocytosis is inherited in an autosomal dominant manner.[3][4][5]. This means that to be have mastocytosis, a person only needs a disease-causing genetic change in one copy of the KIT gene. A person with familial mastocytosis has a 50% chance with each pregnancy of passing along the changed gene to his or her child.
Last updated: 2/22/2018
Mastocytosis is often first suspected by a doctor when a person has signs and symptoms of the disease. A diagnosis of mastocytosis that causes skin lesions may be confirmed by a skin biopsy of the lesion. During a skin biopsy, a sample of skin tissue is taken and looked at under a microscope for the presence of dense areas of mast cells. If there are no cutaneous lesions or if the skin biopsy reveals uncertain results, a bone marrow biopsy may be performed. This procedure can also be useful in differentiating between cutaneous and systemic mastocytosis.[2] 

Blood and/or urine tests may also be used to measure the levels of specific chemicals or substances related to mast cells. High levels of certain substances support the diagnosis of mastocytosis. Some substances may be elevated in systemic mastocytosis but not in cutaneous mastocytosis. Other evaluations or tests used to confirm a diagnosis may include a bone scan, gastrointestinal workup, or genetic testing to confirm there is a mutation in the KIT gene.[6] 

Additional tests may be ordered to rule out other diseases that may cause similar symptoms, such as anaphylaxis, pheochromocytoma, carcinoid syndrome, or Zollinger-Ellison syndrome.[6]
Last updated: 2/22/2018

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
The treatment for mastocytosis depends on the particular symptoms of each person. Treatment for symptoms that affect the skin include antihistamines and oral psoralen plus UVA (PUVA) therapy. If the symptoms are not responsive to other treatment, a doctor may prescribe steroid creams, ointments, or solutions to be applied to the skin (topical corticosteroids treatment).[1] Proton pump inhibitors can be used to treat gastrointestinal symptoms and bone pain. Different treatments work better for some people than others.[1]

Many specialists recommended that people with mastocytosis have injectable epinephrine that they can use in case of anaphylactic shock. Other recommendations include trying to avoid known triggers of symptoms of mastocytosis.[7]
Last updated: 2/22/2018

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

Mastocytosis is described as a rare disease, but to our knowledge, the exact incidence and prevalence are not known.[1] A diseaseis considered rare if it affects fewer than 200,000 people in the United States at any given time. An estimate of prevalence from a recent population-based study is approximately 1 case per 10,000 people.[8]

While mastocytosis in general affects males and females in equal ratios, there appears to be a slight male predominance in childhood and a slight female predominance in adulthood. In children, 80% of cases appear during the first year of life, and the majority is limited to the skin. Adults who develop mastocytosis more often have systemic forms of the disease. Cutaneous forms of the disease account for less than 5% of adult cases.[1]
Last updated: 11/18/2015

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Mastocytosis. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.
  • The Research Portfolio Online Reporting Tool (RePORT) provides access to reports, data, and analyses of research activities at the National Institutes of Health (NIH), including information on NIH expenditures and the results of NIH-supported research. Although these projects may not conduct studies on humans, you may want to contact the investigators to learn more. To search for studies, enter the disease name in the "Text Search" box. Then click "Submit Query".

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Social Networking Websites

  • RareConnect has an online community for patients and families with this condition so they can connect with others and share their experiences living with a rare disease. The project is a joint collaboration between EURORDIS (European Rare Disease Organisation) and NORD (National Organization for Rare Disorders).

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Merck Manual for health care professionals provides information on Mastocytosis.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Mastocytosis. Click on the link to view a sample search on this topic.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • I am wondering about the estimated number of people having been diagnosed with this disease. I have it, but have not been diagnosed yet. See answer

  • Is mastocytosis contagious? See answer

  • Is mastocytosis hereditary? See answer


  1. Castells MC and Akin C. Mastocytosis (cutaneous and systemic): Epidemiology, pathogenesis, and clinical manifestations. UpToDate. December 5, 2016; http://www.uptodate.com/contents/mastocytosis-cutaneous-and-systemic-epidemiology-pathogenesis-and-clinical-manifestations.
  2. Bundra K and Akin C. Mastocytosis. National Organization for Rare Disorders. 2017; https://rarediseases.org/rare-diseases/mastocytosis/.
  3. Fett NM, Teng J, and Longley BJ. Familial urticaria pigmentosa: report of a family and review of the role of KIT mutations. Am J Dermatopathol. February 2013; 35(1):113-116. https://www.ncbi.nlm.nih.gov/pubmed/22892471.
  4. de Melo Campos P, Machado-Neto JA, Scopim-Ribeiro R, Visconte V, Tabarroki A, Duarte AS, Barra FF, Vassalo J, Rogers HJ, Lorand-Metze I, Tiu RV, Costa FF, Olalla Saad ST, and Traina F. Familial systemic mastocytosis with germline KIT K509I mutation is sensitive to treatment with imatinib, dasatinib and PKC412. Leuk Res. October 2014; 38(10):1245-1251. https://www.ncbi.nlm.nih.gov/pubmed/25139846.
  5. Mast Cell Disease. Online Mendelian Inheritance in Man (OMIM). January 24, 2012; http://omim.org/entry/154800.
  6. Delves PJ. Mastocytosis. Merck Manual. June 2016; http://www.merckmanuals.com/professional/immunology-allergic-disorders/allergic-autoimmune-and-other-hypersensitivity-disorders/mastocytosis.
  7. Habashy J and Robles DT. Mastocytosis. Medscape Reference. May 15, 2017; http://emedicine.medscape.com/article/1057932-overview.
  8. Theoharides TC, Valent P, and Akin C. Mast Cells, Mastocytosis, and Related Disorders. N Engl J Med. July 9, 2015; 373(2):163-172. https://www.ncbi.nlm.nih.gov/pubmed/26154789.