Cutaneous mastocytosis

What causes cutaneous mastocytosis?

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.

Last updated on 05-01-20

How is cutaneous mastocytosis diagnosed?

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.

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.

Last updated on 05-01-20

Is cutaneous mastocytosis inherited?

Most cases of cutaneous mastocytosis are not inherited. They occur spontaneously in families with no history of the condition and are due to somatic changes (mutations) in the KIT gene. Somatic mutations occur 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.

Cutaneous mastocytosis can rarely affect more than one family member. In these cases, the condition is typically inherited in an autosomal dominant manner. This means that to be affected, a person only needs a change (mutation) in one copy of the responsible gene in each cell. A person with familial cutaneous mastocytosis has a 50% chance with each pregnancy of passing along the altered gene to his or her child.

Last updated on 05-01-20

What is the long-term outlook for people with cutaneous mastocytosis?

The long-term outlook (prognosis) for people affected by cutaneous mastocytosis varies depending on the age at diagnosis. The prognosis is typically excellent in children who develop symptoms before age 2 as approximately 80% of these cases resolve before puberty. The remaining cases may persist as cutaneous mastocytosis or progress to systemic disease. Risk factors for progression to systemic mastocytosis include later onset of the skin symptoms (after age 2), persistence of skin symptoms past adolescence, and abnormal blood counts. In very rare cases, the condition may progress to aggressive forms of mast cell disease such as mast cell sarcoma (solid tumor of cancerous mast cells) or mast cell leukemia (rare disease of circulating cancerous mast cells).

Cutaneous mastocytosis that develops after age 2 or in adults generally does not resolve. Approximately 90% of affected adults also have evidence of systemic mastocytosis at the time of diagnosis. Later onset cases also have a higher risk of malignant (cancerous) forms of mast cell disease.

Last updated on 05-01-20

How might cutaneous mastocytosis be treated?

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.

Last updated on 05-01-20

Where To Start

Cutaneous mastocytosis

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.

Last updated on 04-27-20

Name: The Mastocytosis Society P.O. Box 416
Sterling, MA, 01564, United States
Email: Url:

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