Recognizing hallmark symptoms may help with earlier identification of SM1

Skin lesions, anaphylaxis, diarrhea?
Suspect systemic mastocytosis (SM)

Symptoms of SM can mimic other disorders

Select each circle to see how these disorders are different than SM


Cutaneous mastocytosis2-5

The skin is the only site of involvement in CM, whereas SM affects other organs besides skin.

97% of patients (N=59) presenting with adult-onset CM actually have SM.*

Mast cell activation syndrome

Mast cell activation

Bone marrow biopsies for patients with MCAS may show 1 or 2 minor criteria for SM but do not fulfill the complete
WHO criteria.

A full diagnostic workup, including high-sensitivity KIT D816V testing, could help in making a differential diagnosis.



Urticaria pigmentosa is thought to be a self-resolving condition. Unlike forms of mastocytosis, there is rarely any internal organ involvement, as would be found in patients with SM.



SM can cause GI symptoms similar to IBD, but mast cells may only mildly increase with IBD and aggregates of mast cells would not be observed.



~70% of patients with advanced SM have an associated neoplasm (CMML, MPN, MDS). A specific diagnosis for SM requires a number of laboratory studies, including a high-sensitivity KIT D816V assay.



GI symptoms are present in 60%–80%
of SM patients.

SM-related GI symptoms are largely caused by release of mediators and in rare, advanced forms by mast cell infiltration of the gut causing malabsorption.

Endocrine disorders

Endocrine disorders2,10

While endocrine disorders can cause flushing, recurrent, unexplained flushing may raise suspicion for SM.

Review case studies
to see how high-sensitivity
KIT D816V testing can help
confirm SM6

  • *Based on a study with 59 patients with the clinical diagnosis of adult-onset mastocytosis in the skin established between 2004 and 2008.5
    CM=cutaneous mastocytosis; CMML=chronic myelomonocytic leukemia; GI=gastrointestinal; IBD=inflammatory bowel disease; IBS=irritable bowel syndrome; 
    MCAS=mast cell activation syndrome; MDS=myelodysplastic syndrome; MPN=myeloproliferative neoplasm.

High-sensitivity KIT D816V testing can be used as a first step to evaluate SM upon clinical suspicion6

Additional testing is required for diagnosis and subtyping.

Suspect SM?1

  • Presence of:
  • Hallmark symptoms
    (skin lesions, anaphylaxis, diarrhea)
  • Symptoms of mast cell activation
  • Elevated serum tryptase

Test for a leading indicator in diagnosis of SM6

High-sensitivity KIT D816V testing
(eg, ASO-qPCR or ddPCR)6

KIT D816V is the main driver of disease in ~95% of SM cases11-13

Patients who test positive
for KIT D816V using
high-sensitivity KIT testing have an increased
likelihood of SM6,11-13

Serum tryptase should always be measured in patients with
suspected SM.14

  •  ASO-qPCR=allele-specific oligonucleotide quantitative polymerase chain reaction; ddPCR=droplet digital PCR.
Woman with hand on chest

Did you know?

Low-sensitivity assays may fail to detect the KIT D816V mutation and potentially prolong diagnosis6


Explore case studies of the types of patients
you may see in your practice

The profiles below are examples of different patient types, which may help you recognize patients in your practice who may be at risk of SM. Patient profiles are fictionalized through review of published literature and are not actual patients.

Select each of the cases below
to learn more

Patient Gregory headshot

Gregory, Age 67

Presenting to his hematologist/oncologist

Not an actual patient.

Patient Katherine headshot

Katherine, Age 42

Presenting to her dermatologist

Not an actual patient.

Patient Martha headshot

Martha, Age 53

Presenting to ER

Not an actual patient.

Patient Peter headshot

Peter, Age 55

Presenting to his gastroenterologist

Not an actual patient.

Screen suspected patients
high-sensitivity KIT D816V assays

Click to expand references.

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© 2023 Blueprint Medicines Corporation.

10/2022     USBP-PRSM-22.016.1

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