SM presents with symptoms from skin lesions to fatigue that diminish everyday living, to organ damage that can reduce survival^1–3

Mast cell-mediator symptoms in SM can be unpredictable and identifying the underlying disease often takes years. SM symptoms can be triggered by aspects of everyday life, including heat, stress, exercise and food, although these triggers vary considerably and are not always representative¹

Explore a range of potential clinical consequences across multiple organ systems for patients with SM

Body diagram showing SM symptoms across organ systems

Note: Not an exhaustive list of possible symptoms. The frequency and intensity of any given symptom may vary from person to person.

Common symptoms such as skin lesions, anaphylaxis and diarrhoea should raise suspicion of SM^1,2,6

Download the symptom checklist to help you recognise the symptoms or features indicative of SM

Skin

Skin manifestations in ISM and Advanced SM

It is estimated that around 95% of ISM patients and around 50% of Advanced SM patients experience maculopapular skin lesions^7*

Small monomorphic lesions often appear on the thighs or trunk of the body⁷
A wheal-and-flare reaction is induced by stroking lesions mechanically, e.g. with tongue spatula⁷
In the PRISM trial, 28% of patients with SM stated skin symptoms as their most bothersome symptom^3†

Reproduced with permission from ©DermNet www.dermnetnz.org 2025.

Download the skin lesions leaflet to learn more

Blood cell abnormalities

Liver/spleen

Musculoskeletal

Systemic organ damage in Advanced SM

Patients with Advanced SM can experience organ damage, including ascites, osteolytic lesions, liver dysfunction, weight loss, cytopenia and hypersplenism^2,5
The presence of persistent non-chemotherapy-specific symptoms in patients with AHNs should prompt suspicion of SM^6,8

Consider further diagnostic workup in patients with persistent or unexplained symptoms, especially when accompanied by abnormal blood counts or suspected myeloid neoplasms^6,8,9

Differential diagnosis >

Systemic

Neurocognitive

Systemic debilitating symptoms in all SM subtypes

Any patient living with SM can present with potentially severe symptoms, from brain fog and fatigue to life-threatening anaphylaxis, that diminish everyday quality of life:^1-3

About 33% of patients living with SM experience anaphylaxis;^1‡ it is commonly triggered by hymenoptera stings or may occur as unexplained or idiopathic anaphylaxis⁵
At least 60% of patients living with SM experience difficulty concentrating or bothersome fatigue^1‡
The unpredictable onset of acute symptoms is a main reason that patients with mast cell diseases seek support¹

*As described by the expert panel review of adult-onset mastocytosis (predominantly indolent population) in the Hartmann 2016 study.⁷
^†Based on data from the EU PRISM Patient Survey on the impact of SM (N=540).³
^‡Based on data from the Mast Cell Connect Registry (N=163) in the Jennings 2018 study.¹

Characteristics of indolent systemic mastocytosis

Advanced systemic mastocytosis – important aspects in clinical practice

Recognising severe and recurrent instances of the common symptoms can help raise suspicion of SM, even within a concomitant diagnosis⁶

Initial screening upon suspicion can guide the need for next steps or referral

Screening before referral >

Screening following referral can help confirm or rule out the diagnosis

Screening after referral >

Learn about the impact of SM on patients' quality of life

Burden of disease >

References V

Jennings SV, et al. Immunol Allergy Clin North Am. 2018;38(3):505–525.
Pardanani A. Am J Hematol. 2023;98(7):1097–1116.
Triggiani M, et al. Clin Exp Allergy. 2025;55(9):784–794.
van Anrooij B, et al. Allergy. 2016;71(11):1585–1593.
Gülen T, et al. J Intern Med. 2016;279(3):211–228.
Valent P, et al. J Allergy Clin Immunol Pract. 2022;10(8):1999–2012.e6.
Hartmann K, et al. J Allergy Clin Immunol. 2016;137(1):35–45.
Rets A, George TI. Int J Lab Hematol. 2025. doi: 10.1111/ijlh.70011. Online ahead of print.
Schwaab J, et al. J Allergy Clin Immunol Pract. 2020;8(9):3121–3127.e1.

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SM presents with symptoms from skin lesions to fatigue that diminish everyday living, to organ damage that can reduce survival1–3