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

Systemic mastocytosis


Other Names:
Systemic mast cell disease; SMCD
Categories:
This disease is grouped under:
Systemic mastocytosis (SM) is a form of mastocytosis in which mast cells accumulate in internal tissues and organs such as the liver, spleen, bone marrow, and small intestines. It is typically diagnosed in adults. Signs and symptoms vary based on which parts of the body are affected. The disorder is usually caused by somatic changes (mutations) in the KIT gene.[1][2] Most cases are sporadic and not inherited, but familial cases rarely have been reported.[3] 

Systemic mastocytosis can be divided into 4 main categories which are distinguished by various features:[4]
Once a person is diagnosed, the category of SM must be determined, as treatment and prognosis differ for each.[4]
Last updated: 9/6/2016
In systemic mastocytosis (SM), mast cells accumulate in internal organs such as the liver, spleen, bone marrow, and small intestines. The signs and symptoms vary based on which parts of the body are affected but may include:[1][2]
  • Anemia and bleeding disorders
  • Gastrointestinal symptoms such as abdominal pain, diarrhea, nausea, and/or vomiting
  • Itching, hives, and/or flushing of the skin
  • Anaphylactoid reactions
  • Enlarged liver (hepatomegaly), spleen (splenomegaly), and lymph nodes (lymphadenopathy)
There are four main types of systemic mastocytosis which vary in severity. They include:[4]
  • Indolent systemic mastocytosis - the most common form of SM with a slowly progressive (worsening over time) clinical course
  • Systemic mastocytosis with an associated hematologic nonmast cell lineage disorder - a form of SM associated with other blood disorders (such as myeloproliferative or myelodysplastic conditions)
  • Aggressive systemic mastocytosis - a severe form of SM usually characterized by organ impairment or organ failure due to aggressive mast cell infiltration
  • Mast cell leukemia - a very rare and aggressive form of SM that is associated with greater than 10% immature mast cells in the peripheral blood or greater than 20% immature mast cells in bone marrow cultures
Last updated: 9/6/2016

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 37 |
Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Abdominal pain
Pain in stomach
Stomach pain
[ more ] 		0002027
Abnormal eosinophil morphology 0001879
Headache
Headaches
0002315
Malabsorption
Intestinal malabsorption
0002024
Mastocytosis 0100495
Nausea and vomiting 0002017
Urticaria
Hives
0001025
30%-79% of people have these symptoms
Anemia
Low number of red blood cells or hemoglobin
0001903
Generalized osteosclerosis 0005789
Impaired temperature sensation
Abnormality of temperature sensation
Loss of temperature sensation
[ more ] 		0010829
Leukopenia
Decreased blood leukocyte number
Low white blood cell count
[ more ] 		0001882
Osteoporosis 0000939
Skin rash 0000988
Thrombocytopenia
Low platelet count
0001873
5%-29% of people have these symptoms
Abnormality of the gastric mucosa
Abnormality of the mucous membrane layer of stomach
0004295
Acute leukemia 0002488
Arthralgia
Joint pain
0002829
Ascites
Accumulation of fluid in the abdomen
0001541
Asthma 0002099
Bone marrow hypocellularity
Bone marrow failure
0005528
Bone pain 0002653
Chronic leukemia 0005558
Cirrhosis
Scar tissue replaces healthy tissue in the liver
0001394
Hepatomegaly
Enlarged liver
0002240
Lymphadenopathy
Swollen lymph nodes
0002716
Myalgia
Muscle ache
Muscle pain
[ more ] 		0003326
Osteolysis
Breakdown of bone
0002797
Portal hypertension 0001409
Recurrent fractures
Increased fracture rate
Increased fractures
Multiple fractures
Multiple spontaneous fractures
Varying degree of multiple fractures
[ more ] 		0002757
Splenomegaly
Increased spleen size
0001744
Sudden cardiac death
Premature sudden cardiac death
0001645
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
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Last updated: 7/1/2020
Most cases of systemic mastocytosis are caused by somatic mutations in the KIT gene. This gene encodes 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 (immune cells that are important for the inflammatory response). Mutations in the KIT gene can leads to an overproduction of mast cells, which then accumulate in internal organs and lead to the symptoms of this condition.[5][2]
Last updated: 9/6/2016
Most cases of systemic mastocytosis (SM) are sporadic (not inherited), occurring in people with no family history of the condition. The genetic mutations that often cause SM are somatic, which means they are acquired after conception and are only present in certain cells. Because they are not present in the germ cells (egg and sperm), they are not passed on to the next generation.[1]

Rarely, SM has been reported in more than one family member. In this case, it may be inherited in an autosomal dominant manner.[3] Mutations that cause autosomal dominant conditions are located in the germ cells. To be affected with an autosomal dominant condition, a person needs to have a mutation in only one copy of the responsible gene in each cell. A person with this form of SM has a 50% chance with each pregnancy of passing the mutation to his or her child.
Last updated: 9/6/2016
A diagnosis of systemic mastocytosis (SM) is often suspected based on the presence of characteristic signs and symptoms. Additional testing can then be ordered to rule out other conditions with similar features; confirm the diagnosis; determine the type; and assess the severity. These tests may include:[2]
  • Bone marrow biopsy - the most useful test used to diagnose the condition
  • Blood studies - may show anemia, elevated histamine levels, thrombocytopenia, high white blood cell count (leukocytosis), low blood albumin levels (hypoalbuminemia), or high serum tryptase levels
  • Imaging studies - may help to identify the extent and stage of the disease
  • Biopsies of affected organs (such as the liver and/or skin)
  • Genetic testing
More information about studies used to diagnose SM can be viewed here on the Medscape Reference website.
Last updated: 9/6/2016

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.
Treatment for systemic mastocytosis (SM) is based on the signs and symptoms present in each person. For example, the following medications may used to treat various symptoms associated with SM:[2][6]
  • Antihistamines to treat or prevent skin and gastrointestinal symptoms
  • Proton pump inhibitors to treat increased stomach acid
  • Epinephrine to treat anaphylaxis
  • Steroids to treat malabsorption (impaired ability to take in nutrients)
  • Mast-cell stabilizers such as ketotifen to treat some of the skin symptoms
  • Cromolyn sodium to treat gastrointestinal symptoms, bone pain, headaches, and some of the skin manifestations
If systemic mastocytosis is cancerous (mast cell leukemia) or associated with a blood disorder, steroids and/or chemotherapy may be necessary.[7]

More specific information about treatment options can be accessed through the Treatment and Medication sections of the Medscape Reference website.
Last updated: 9/6/2016

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.

  • Midostaurin (Brand name: Rydapt) - Manufactured by Novartis Oncology
    FDA-approved indication: Treatment of adult patients with aggressive systemic mastocytosis (ASM), systemic mastocytosis with associated hematological neoplasm (SM-AHN), or mast cell leukemia (MCL).
    National Library of Medicine Drug Information Portal
The long-term outlook (prognosis) for people with systemic mastocytosis (SM) varies. Young children and those who present with primarily cutaneous (skin) and flushing symptoms tend to have little or no progression of the disease over a considerable length of time. Older patients and those with extensive, systemic disease involving other organ systems have a poorer prognosis. The median duration of survival is in these cases is not known but appears to be a few years.[2]

Features that may be associated with a poorer prognosis may include:[6][2]
  • elevated lactate dehydrogenase levels
  • anemia
  • thrombocytopenia (low platelet count)
  • hypoalbuminemia (low albumin)
  • excess bone marrow blasts (>5%)
  • high alkaline phosphatase
  • hepatosplenomegaly (enlarged liver and/or spleen)
  • ascites
Last updated: 6/17/2015

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

Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Differential diagnoses of SM include all the other causes of mast cell activation syndromes (MCAS): primary (clonal, but not fulfilling SM diagnostic criteria) MCAS; secondary MCAS where an IgE-dependent allergy (most cases) or another reactive inflammatory disease process is present (and is considered to be the causative etiology); and idiopathic MCAS where neither clonal MC nor an IgE-dependent allergy or another underlying condition/disease can be documented. As well, differential diagnoses include other forms of mastocytosis (cutaneous mastocytosis, mast cell sarcoma), endocrine disorders (adrenal tumors, VIPoma,, Zollinger-Ellison syndrome), some gastrointestinal pathologies, allergies, other myeloproliferative diseases that affect bone marrow, histiocytosis, hypereosinophilic syndrome and Waldenström macroglobulinemia.
Visit the Orphanet disease page for more information.

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 Systemic 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.

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 Systemic 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 Systemic 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

  • My 22 year old son was diagnosed with urticaria pigmentosa in infancy and except for skin spots he is largely symptom-free. Because of increasing skin spots and elevated serum tryptase, he had bone marrow tests and was diagnosed with indolent systemic mastocytosis (ISM). He does not have other health problems and is very active. Will his symptoms worsen systemically with time or is it possible for ISM patients to remain symptom-free for life? See answer

  • My mother is suffering from systemic mastocytosis. What types of treatment are available for this condition? See answer

  • I need information on the initial tests that can be done to rule out systemic mastocytosis. What are they and should they be done after an episode or can they be done at any time? See answer

  • Can heat and/or humidity affect systemic mastocytosis? See answer


  1. Bundra K and Akin C. Mastocytosis. National Organization for Rare Disorders. 2017; https://rarediseases.org/rare-diseases/mastocytosis/.
  2. Koyamangalath Krishnan. Systemic Mastocytosis. Medscape Reference. April 22, 2016; http://emedicine.medscape.com/article/203948-workup#showall.
  3. 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.
  4. Mariana C Castells and Cem Akin. Systemic mastocytosis: Determining the category of disease. UpToDate. Waltham, MA: UpToDate; August, 2016;
  5. KIT. Genetics Home Reference. September 2014; http://ghr.nlm.nih.gov/gene/KIT.
  6. Castells MC and Akin C. Systemic mastocytosis: Treatment and prognosis. UpToDate. October 21 2016; http://www.uptodate.com/contents/systemic-mastocytosis-treatment-and-prognosis.
  7. Mastocytosis. National Institute of Allergy and Infectious Diseases (NIAID). October 2013; http://www.niaid.nih.gov/topics/mastocytosis/Pages/Treatment.aspx.