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Disease Profile

Cutaneous mastocytosis

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset






Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.


Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)



Cutaneous mastocytosis is a form of mastocytosis that primarily affects the skin. There are three main forms of the condition: maculopapular cutaneous mastocytosis (also called urticaria pigmentosa), solitary cutaneous mastocytoma, and diffuse cutaneous mastocytosis. There is also an exteremely rare form called telangiectasia macularis eruptiva perstans. The signs, symptoms and severity of the condition vary by subtype.[1][2][3] Cutaneous mastocytosis is usually caused by changes (mutations) in the KIT gene. Most cases are caused by somatic mutations which are not inherited or passed on to the next generation.[1] However, it can rarely affect more than one family member and be inherited in an autosomal dominant manner.[4] Treatment is usually symptomatic and may include oral antihistamines, topical steroids, and/or photochemotherapy.[1][5]


Cutaneous mastocytosis is a form of mastocytosis that primarily affects the skin. There are three main forms that vary in severity: maculopapular cutaneous mastocytosis (also called urticaria pigmentosa), solitary cutaneous mastocytoma, and diffuse cutaneous mastocytosis. There is also an exteremely rare form called telangiectasia macularis eruptiva perstans.[2][6]

Maculopapular cutaneous mastocytosis, the most common form of cutaneous mastocytosis, is characterized by itchy, brown patches on the skin. Although these patches may be mistaken for freckles or bug bites initially, they typically persist and gradually increase in number over several months to years. In young children, the patches may form a blister if itched or rubbed. Itching may worsen with changes in temperature, strenuous activity, emotional stress, and/or certain medications. Maculopapular cutaneous mastocytosis is most commonly seen in infants and young children and often fades by the teenaged years. In some cases, this condition may not develop until adulthood. These later onset cases generally last long-term and are more likely to progress to systemic mastocytosis.[2][6][7]

Solitary cutaneous mastocytoma is a localized form of cutaneous mastocytosis. Like maculopapular cutaneous mastocytosis, this form is typically diagnosed in young children. However, it is characterized by an itchy area of reddish or brown skin that is often thickened. When itched, these patches of skin may swell, redden, and/or blister. This form typically resolves spontaneously with age.[2][6][8]

Diffuse cutaneous mastocytosis, the most severe form of cutaneous mastocytosis, usually develops in infancy. Unlike the other forms of cutaneous mastocytosis, it affects most or all of the skin rather than appearing as distinct patches. In people affected by this condition, the skin is leathery and thickened. It may appear normal, yellowish-brown, or red in color. In some cases, there may also be widespread blistering. Additional symptoms may include hypotension, diarrhea, gastrointestinal bleeding, reddening of the skin (flushing), and anaphylactic shock.[1][2][6]

The rarest form of cutaneous mastocytosis is called telangiectasia macularis eruptiva perstans. Unlike the other forms of cutaneous mastocytosis, this form is primarily diagnosed in adults and is generally not associated with pruritus and blistering. People affected by this condition have persistent brown patches of skin and extensive telegiactasia. Rarely, this form may progress to systemic mastocytosis.[1][2]

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.

Medical Terms Other Names
Learn More:
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 ]

Cutaneous mastocytosis
Flat, discolored area of skin
Multiple cafe-au-lait spots
Itchy skin
Skin itching

[ more ]

30%-79% of people have these symptoms
Abdominal pain
Pain in stomach
Stomach pain

[ more ]

5%-29% of people have these symptoms
Abnormal blistering of the skin
Blistering, generalized

[ more ]

Hair loss
Excessive, persistent worry and fear
Cardiac arrest
Heart stops beating
Watery stool
Trouble breathing

[ more ]

Gastrointestinal hemorrhage
Gastrointestinal bleeding
Enlarged liver
High blood calcium levels
Increased calcium in blood

[ more ]

Low blood pressure
Increased bone mineral density
Increased bone density
Myeloproliferative disorder
Nausea and vomiting
Recurrent fractures
Increased fracture rate
Increased fractures
Multiple fractures
Multiple spontaneous fractures
Varying degree of multiple fractures

[ more ]

Cancer of connective tissue
Malignant connective tissue tumor

[ more ]

Increased spleen size
Telangiectasia of the skin


Most cases of cutaneous mastocytosis are caused by changes (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). Certain mutations in the KIT gene can leads to an overproduction of mast cells. In cutaneous mastocytosis, excess mast cells accumulate in the skin, leading to the many signs and symptoms of the condition.[1][9]


A diagnosis of cutaneous mastocytosis is typically suspected based on the presence of suspicious signs and symptoms. A skin biopsy that reveals a high number of mast cells (immune cells that are important for the inflammatory response) confirms the diagnosis.[1][6]

Unfortunately it can sometimes be difficult to differentiate cutaneous mastocytosis from systemic mastocytosis. Additional tests may, therefore, be ordered to further investigate the risk for systemic disease. A bone marrow biopsy and specialized blood tests may be recommended in adults with cutaneous mastocytosis since they are at a higher risk for systemic mastocytosis. Affected children typically do not undergo a bone marrow biopsy unless blood tests are abnormal.[11]

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.
  • Orphanet lists international laboratories offering diagnostic testing for this condition.


    Although there is currently no cure for cutaneous mastocytosis, treatments are available to manage the symptoms of the condition. In general, it is recommended that affected people avoid things that trigger or worsen their symptoms when possible. Certain medications such as oral antihistamines and topical steroids are often prescribed to relieve symptoms. Affected adults may also undergo photochemotherapy which can help alleviate itching and improve the appearance of the patches; however, the condition is likely to recur within six to twelve months of the last treatment. People at risk for anaphylactic shock and/or their caregivers should be trained in how to recognize and treat this life-threatening reaction and should carry an epinephrine autoinjector at all times.[1][5][6]


    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).

        Learn more

        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

        • DermNet NZ is an online resource about skin diseases developed by the New Zealand Dermatological Society Incorporated. DermNet NZ provides information on maculopapular cutaneous mastocytosis and mastocytoma, which are two specific types of cutaneous mastocytosis.
        • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
        • The Merck Manuals Online Medical Library provides information on this condition for patients and caregivers.
        • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.
        • The Mast Cell Disease Society provides information about mast cell diseases, including Cutaneous mastocytosis.

          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 Cutaneous 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.
          • 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 Cutaneous mastocytosis. Click on the link to view a sample search on this topic.


            1. Mastocytosis. DermNet NZ. September 2014; https://dermnetnz.org/systemic/mastocytosis.html.
            2. Castells MC and Akin C. Mastocytosis (cutaneous and systemic): Epidemiology, pathogenesis, and clinical manifestations. UpToDate. December 5, 2016; https://www.uptodate.com/contents/mastocytosis-cutaneous-and-systemic-epidemiology-pathogenesis-and-clinical-manifestations.
            3. Habashy J and Robles DT. Mastocytosis. Medscape Reference. May 15, 2017; https://emedicine.medscape.com/article/1057932-overview.
            4. 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.
            5. CastellsMC and Akin C. Treatment and prognosis of cutaneous mastocytosis. UpToDate. June 5 2015; https://www.uptodate.com/contents/treatment-and-prognosis-of-cutaneous-mastocytosis.
            6. Bundra K and Akin C. Mastocytosis. National Organization for Rare Disorders. 2017; https://rarediseases.org/rare-diseases/mastocytosis/.
            7. Maculopapular cutaneous mastocytosis. DermNet NZ. November 2014; https://dermnetnz.org/colour/urticaria-pigmentosa.html.
            8. Mastocytoma. DermNet NZ. March 2014; https://dermnetnz.org/lesions/mastocytoma.html.
            9. KIT. Genetics Home Reference. September 2014; https://ghr.nlm.nih.gov/gene/KIT.
            10. Mast Cell Disease. Online Mendelian Inheritance in Man (OMIM). January 24, 2012; https://omim.org/entry/154800.
            11. Mariana C Castells, MD, PhD; Cem Akin, MD, PhD. Evaluation and diagnosis of mastocytosis (cutaneous and systemic). UpToDate. July 25 2015; https://www.uptodate.com/contents/mastocytosis-cutaneous-and-systemic-evaluation-and-diagnosis-in-adults.

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