Being diagnosed with systemic mastocytosis (SM) is often challenging, as many of the associated symptoms are not unique to the disease.
There are several differential diagnoses of systemic mastocytosis, including mast cell activation syndrome, carcinoid syndrome, VIPoma and Zollinger-Ellison syndrome. Thorough physical and laboratory exams can help determine the correct diagnosis.
What is SM?
SM is a rare white blood cell disorder which first occurs in both men and women aged 40 to 50 years, where abnormal mast cells develop and accumulate in the tissue, bone and organs of the body. As part of the immune system, mast cells release histamines and other chemicals to protect the body against bacteria and allergens. In SM, excessive activity by mast cells causes inflammation and symptoms such as skin itchiness, hives, flushing of the face, digestive problems, abdominal pain, mood disturbances, bone and muscle pain, palpitations, and in the most severe cases, anaphylaxis.
The symptom burden can vary from person to person, and learning to avoid triggering an allergic reaction is an essential part of managing the disease and supporting daily quality of life. Some triggers include sudden changes in temperature, emotional stress, physical exertion, certain foods, friction on the skin, insect stings, alcohol and some medications. As well as symptom management, antihistamines are prescribed to reduce flushing, itching, abdominal pain and diarrhea.
Learn more about SM signs and symptoms
Conditions similar to systemic mastocytosis
Here are some of the conditions that present with symptoms that mimic those of systemic mastocytosis.
Mast cell activation syndrome (MCAS)
Mast cell activation syndrome and systemic mastocytosis are both mast cell disorders. Where they differ is that MCAS also presents with symptoms of urticaria, angioedema, hypotension, dermatographia, bloating, hiccups, rhinorrhea, sneezing and wheezing.
Carcinoid syndrome
Carcinoid syndrome occurs in people with neuroendocrine tumors (NETs) and presents with a collection of symptoms that could be mistaken for systemic mastocytosis.
The tumors release serotonin and other proteins into the bloodstream, causing symptoms such as flushing and itchiness of the skin, diarrhea, abdominal pain, palpitations, fluid buildup in the legs, wheezing and spidery veins.
VIPoma
Vasoactive Intestinal Peptide-Secreting Tumor (VIPoma) is also a type of neuroendocrine tumor (NET).
Symptoms that mimic systemic mastocytosis include diarrhea, gastrointestinal issues, abdominal pain and flushing.
Zollinger-Ellison syndrome
Zollinger-Ellison syndrome is a rare digestive condition that leads to excess gastric acid in the stomach. This results in symptoms such as nausea, vomiting, abdominal pain and diarrhea.
These differential diagnoses of SM can delay the process of accurately diagnosing the disease. Only through careful documenting of a patient’s symptom history, blood and urine analysis, imaging tests such as ultrasound, CT and MRI and eventually a biopsy, can the correct diagnosis be reached.
