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Systemic mastocytosis (SM): A complex and potentially debilitating mast cell disorder1-3

What is SM?

SM is a clonal mast cell neoplasm associated with the uncontrolled proliferation and activation of abnormal mast cells throughout the body.1-3

SM is primarily driven by the KIT D816V mutation, which is present in ~95% of cases.4-6

Estimated indidence

~1 in 10,000

US adults4

Although the true incidence of SM is unknown

Indolent systemic mastocytosis (ISM) represents the largest subtype of SM6-8

A diagnosis of SM is categorized into subtypes that fall along a clinical spectrum based on disease burden, including ISM and Advanced SM.1

Regardless of SM subtype, SM can have a

detrimental impact to patients

living with the disease1


Challenges in recognizing SM can result in a prolonged time to diagnosis

Because of its heterogeneous and nonspecific symptoms, SM is often mistaken for other disorders.3 Receiving an accurate diagnosis can take an average of ~6 years from symptom onset.9

The delay in diagnosis is notable given the detrimental long-term effects that SM can have on patients, such as decreased overall survival from organ damage in Advanced SM.2,10

~5% of patients

have their indolent SM progress to more advanced
forms of SM over time11

≤3.5 years

is the median overall survival for patients
with Advanced SM10*

  • *Overall survival was examined in a retrospective study that included 342 consecutive adult patients with SM (included 183 adults with Advanced SM) seen at the Mayo Clinic between 1976 and 2007. In aggressive systemic mastocytosis (ASM) (n=41), overall survival was 41 months; 24 months in systemic mastocytosis with associated hematological neoplasm (SM-AHN) (n=138); and 2 months in mast cell leukemia (MCL) (n=4). Median follow-up was 20.7 months.10

Did you know? Symptoms of SM
in adults can be nonspecific,
manifesting across multiple
organ systems1-3


Patients living with SM can present with a range of unpredictable and potentially severe symptoms that can be triggered by aspects of everyday life.1-3,12


Symptoms of SM may present as mastocytosis in the skin, severe allergic reactions including anaphylaxis, diarrhea, or other mast cell activation syndrome symptoms.1,13

Recognizing SM symptoms is crucial

Explore SM Symptoms