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Don’t fight Systemic mastocytosis alone.
Find your community on the free RareGuru App.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. Most cases are sporadic and not inherited, but familial cases rarely have been reported.
Systemic mastocytosis can be divided into 4 main categories which are distinguished by various features:
Once a person is diagnosed, the category of SM must be determined, as treatment and prognosis differ for each.
Source: GARD Last updated on 05-01-20
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:
There are four main types of systemic mastocytosis which vary in severity. They include:
Last updated on 05-01-20
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.
Last updated on 05-01-20
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:
Last updated on 05-01-20
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.
Rarely, SM has been reported in more than one family member. In this case, it may be inherited in an autosomal dominant manner. 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 on 05-01-20
Yes. Heat appears to be one of the many factors that can trigger a mast cell response.
Other triggers include:
Last updated on 05-01-20
Indolent systemic mastocytosis (ISM) typically progresses slowly or not at all. Symptoms do not always worsen with time. Although mast cell infiltrates can be detected in various organs (including liver, spleen, and gastrointestinal tract), the clinical course is generally indolent.
Fewer than 5% of people with an initial diagnosis of ISM will progress to a more severe form of systemic mastocytosis, such as:
Progression to one of these may occur within months to years from the initial diagnosis. Development of unexplained hematologic (blood-related) abnormalities, hepatosplenomegaly, unexplained weight loss, clotting disorders (coagulopathy), ascites, or gastrointestinal bleeding could mean there is a possibility of disease progression.
While most people with ISM have normal life expectancy, severe disability and death have been reported from anaphylactic episodes.
Last updated on 05-01-20
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.
Features that may be associated with a poorer prognosis may include:
Last updated on 05-01-20
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:
If systemic mastocytosis is cancerous (mast cell leukemia) or associated with a blood disorder, steroids and/or chemotherapy may be necessary.
More specific information about treatment options can be accessed through the Treatment and Medication sections of the Medscape Reference website.
Last updated on 05-01-20
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