Recognising severe and recurrent instances of the common symptoms can help raise suspicion of SM, even within a concomitant diagnosis^1,2

Symptoms of SM can mimic one or more common conditions, leading to frequent misdiagnosis or under-recognition:

Cutaneous mastocytosis (CM)	97% of patients presenting with adult-onset CM have SM^3* A bone marrow examination is recommended to exclude or confirm an SM diagnosis¹
Urticaria	Urticaria (including chronic idiopathic urticaria) may raise the suspicion of CM or SM due to the similar wheal-and-flare responses. Unlike typical urticaria which typically resolves in less than 24 hours after scarring, urticaria pigmentosa in SM forms reddish-brown maculopapular lesions that persist longer^4,5 Download the skin lesions leaflet to help you identify characteristic skin lesions in SM
Endocrine disorders	Endocrine disorders, such as thyroid disorders and adrenal disorders, can cause episodes of flushing and diarrhoea similar to SM⁵
Gastrointestinal (GI) conditions	GI manifestations are present in 15–80% of patients with SM. GI symptoms associated with SM are often non-specific and mimic common conditions such as irritable bowel syndrome, inflammatory bowel disease or coeliac disease.⁶

*Based on a cohort study of 59 patients with adult-onset mastocytosis in the skin in the Berezowska 2014 study.³

Overview of SM

Consider referring patients for unexplained and recurrent symptoms that are common to SM¹

Screening before referral >

Advanced SM may be missed in patients with myeloid neoplasms⁷

Advanced SM predominantly presents with haematological neoplasms of myeloid origin, including CMML, MPN and MDS⁸

Diagnosis of SM in patients with another haematological neoplasm is defined as SM-AHN, a subtype of Advanced SM⁹

AHN=associated haematological neoplasm; AML=acute myeloid leukaemia; CMML=chronic myelomonocytic leukaemia; CEL=chronic eosinophilic leukaemia; MDS=myelodysplastic syndrome; MDS/MPN=myelodysplastic syndrome/myeloproliferative neoplasm; MPN=myeloproliferative neoplasm; SM-AHN=systemic mastocytosis with an associated haematological neoplasm; SM-ALN=systemic mastocytosis with an associated lymphoid neoplasm; SM-AMN=systemic mastocytosis with an associated myeloid neoplasm.

^†Data based on a Mayo Clinic cohort. Only patients with SM-AHN are reported (N=138).¹⁰

"I think primarily it's trying to work out – A, being aware of the possibility of SM being associated with these diseases, and B, is there just something slightly atypical or unusual about this patient that means I need to do those extra tests?"

Dr Jonathan Lambert

The presence of persistent non-chemotherapy-specific symptoms in AHNs should prompt suspicion and further investigation for SM^1,12

Download the SM-AHN leaflet to learn more about identifying SM in AHNs

Symptoms of SM >

Consider further diagnostic workup in patients with persistent or unexplained symptoms, especially when accompanied by abnormal blood counts or suspected myeloid neoplasms^1,7,12

Screening after referral >

References V

Valent P, et al. J Allergy Clin Immunol Pract. 2022;10(8):1999–2012.e6.
Shomali W, Gotlib J. Hematology. 2018;2018(1):127–136.
Berezowska S, et al. Mod Pathol. 2014;27(1):19–29.
Bains SN, Hsieh FH. Ann Allergy Asthma Immunol. 2010;104(1):1–10.
NORD Rare Disease Database. Mastocytosis. Available at: https://rarediseases.org/rare-diseases/mastocytosis/#related-disorders. Accessed October 2025.
Elvevi A, et al. World J Gastroenterol. 2022;28(29):3767–3779.
Schwaab J, et al. J Allergy Clin Immunol Pract. 2020;8(9):3121–3127.e1.
Reiter A, et al. Blood. 2020;135(16):1365–1376.
Valent P, et al. Hemasphere. 2021;5(11):e646.
Pardanani A, et al. Blood. 2009;114(18):3769–3772.
Valent P, et al. J Allergy Clin Immunol Pract. 2024;12(12):3250–3260.e5.
Rets A, George TI. Int J Lab Hematol. 2025. doi: 10.1111/ijlh.70011. Online ahead of print.

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Recognising severe and recurrent instances of the common symptoms can help raise suspicion of SM, even within a concomitant diagnosis1,2

Cutaneous mastocytosis (CM)

Urticaria

Endocrine disorders

Gastrointestinal (GI) conditions

Overview of SM

Consider referring patients for unexplained and recurrent symptoms that are common to SM1

Advanced SM may be missed in patients with myeloid neoplasms7

Consider further diagnostic workup in patients with persistent or unexplained symptoms, especially when accompanied by abnormal blood counts or suspected myeloid neoplasms1,7,12

References V

Stay up to date

Recognising severe and recurrent instances of the common symptoms can help raise suspicion of SM, even within a concomitant diagnosis^1,2

Consider referring patients for unexplained and recurrent symptoms that are common to SM¹

Advanced SM may be missed in patients with myeloid neoplasms⁷

Consider further diagnostic workup in patients with persistent or unexplained symptoms, especially when accompanied by abnormal blood counts or suspected myeloid neoplasms^1,7,12