Mast Cell Activation Syndrome Diagnosis and Symptoms

Core Symptom Pattern

The American Academy of Allergy, Asthma, and Immunology notes that Mast Cell Activation Syndrome (MCAS) presents with acute, recurrent episodes involving at least 2 organ systems simultaneously, with the most diagnostically valuable manifestations being cardiovascular, dermatologic, respiratory, and gastrointestinal symptoms occurring together during discrete episodes 1, 2
The defining characteristic of MCAS is episodic, not continuous symptoms, as stated by the American College of Allergy, Asthma, and Immunology, and persistent or chronic symptoms should direct diagnosis toward alternative diagnoses 2

The American Heart Association notes that cardiovascular symptoms of MCAS include hypotension, tachycardia, and syncope or near-syncope 1, 2
The American Academy of Dermatology notes that dermatologic symptoms of MCAS include flushing, urticaria, pruritus, angioedema, and dermatographism 1, 2, 3
The American Thoracic Society notes that respiratory symptoms of MCAS include wheezing, shortness of breath, and inspiratory stridor 1, 2
The American Gastroenterological Association notes that gastrointestinal symptoms of MCAS include crampy abdominal pain, diarrhea, nausea with vomiting, and abdominal cramping 1, 2, 3

The American College of Allergy, Asthma, and Immunology states that all three criteria must be met for MCAS diagnosis: episodic symptoms affecting ≥2 organ systems concurrently, documented acute increases in mast cell mediators during symptomatic episodes, and clinical response to mast cell-targeted therapies 2

The American Academy of Allergy, Asthma, and Immunology notes that anaphylaxis represents the most severe form of mast cell activation and requires immediate medical attention with epinephrine and supportive care measures 4
The National Comprehensive Cancer Network notes that the risk of perioperative anaphylaxis is estimated to be higher in patients with systemic mastocytosis relative to the general population 3

The American Academy of Allergy, Asthma, and Immunology notes that common triggers that can precipitate episodes include hot water, alcohol, certain drugs, stress, exercise, infection, physical stimuli, and hormonal fluctuations 5
The National Comprehensive Cancer Network notes that temperature extremes and unnecessary trauma should be avoided 3