Atypical SM symptoms: How to recognize them and tell your doctor

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People living with systemic mastocytosis often report different symptoms and triggers, as well as varying severity and duration.

The symptom burden of systemic mastocytosis (SM) has a significant effect on everyday life. 

People living with systemic mastocytosis often report differing experiences of symptom triggers, severity and duration. As mast cells build up in different parts of the body, it is also possible for symptoms to vary from person to person. 

Systemic mastocytosis (SM) is a rare hematological disease characterized by mast cells that are overactive and accumulate in different parts of the body such as the bone marrow, liver, spleen, gastrointestinal tract and lymph nodes.

Excessive mast cell activity leads to an abnormal proliferation of mast cells that build up in the skin, bones, joints, liver, digestive tract and lungs

Read more about SM signs and symptoms

When an immune response is triggered, the effect is amplified, with larger quantities of histamine, cytokines, growth factors and heparin released into the bloodstream. This in turn activates symptom episodes of varying intensity, affecting quality of life, well-being and mental health.

Common symptoms of SM

The most common form of SM, indolent systemic mastocytosis (ISM), accounts for 90% to 95% of cases and mostly presents with mild to moderate symptoms such as itching and flushing of the skin, hives, muscle or joint pain, abdominal pain, vomiting, diarrhea, headache, brain fog, anxiety, low mood, short-term memory loss, wheezing, shortness of breath, fainting and even anaphylaxis in severe cases.

The next most common form, smoldering systemic mastocytosis (SSM), is characterized by the same symptoms as ISM but with greater severity. The main difference is a greater risk of disease progression to a more severe version of SM

Less common symptoms of SM

Another subgroup of systemic mastocytosis is aggressive systemic macrocytosis (ASM) which includes a heavier burden of symptoms that affect the organs, such as enlarged liver and lymph nodes, anemia and low platelets.

This can lead to weight loss, jaundice, lethargy, stomach and shoulder pain. But skin lesions are less common. Life expectancy is also reduced in comparison to ISM and SSM.

Medication and symptom management

As there is no cure for SM, managing symptoms and slowing disease progression are the main treatment focus. Experts recommend keeping a detailed symptom diary to share with your doctor to help optimize your treatment. It will give your doctor information on your disease progression and the efficacy of your medication.

With time you will learn to recognize and avoid your individual symptom triggers. This will improve your quality of life and help reduce the effect of symptoms on your overall health and well-being.

Your doctor will determine a personalized treatment protocol based on your subgroup of SM and your symptom burden. The main medications are skin emollients for dermatological irritation, H1 and H2 antihistamines for skin itchiness and redness, sodium cromoglicate for diarrhea and stomach pain and epinephrine in the case of anaphylaxis.