Summary
Definition
History and exam
Key diagnostic factors
- recurrent episodes of anaphylaxis
- acute-onset cardiovascular symptoms and signs of mast cell activation
- acute-onset skin symptoms and signs of mast cell activation
- acute-onset respiratory/naso-ocular symptoms and signs of mast cell activation
- acute-onset gastrointestinal symptoms and signs of mast cell activation
- allergic or other trigger for acute onset of symptoms
- positive response to mast cell mediator medication
- skin signs of mastocytosis
Other diagnostic factors
- neurological symptoms
- musculoskeletal symptoms
Risk factors
- mastocytosis
- atopic predisposition
- history of unprovoked anaphylaxis
- hereditary alpha-tryptasaemia
Diagnostic investigations
1st investigations to order
- serum tryptase
- urinary metabolites of histamine and/or prostaglandin D2 and/ or leukotriene C4 (LTC4)
- 12-lead ECG
Investigations to consider
- allergy work-up
- peripheral blood KIT D816V mutation analysis
- bone marrow biopsy
- trial of mast cell mediator blocking agent/mast cell stabiliser
Treatment algorithm
acute MCAS: anaphylaxis episode
confirmed MCAS (all subtypes): long-term management
Contributors
Authors
Cem Akin, MD, PhD
Clinical Professor of Allergy and Immunology
University of Michigan Health
Ann Arbor
MI
Disclosures
CA has consultancy agreements with Blueprint Medicines, Cogent, and Novartis, and receives contract research support from Blueprint Medicines and Cogent. CA is also a member of the board of directors of the American Academy of Allergy, Asthma and Immunology (AAAAI).
Theo Gulen, MD, PhD
Senior Consultant Allergist
Department of Respiratory Medicine and Allergic Diseases
Karolinska University Hospital
Karolinska Institutet and Mastocytosis Cente
Stockholm
Sweden
Disclosures
TG declares that he has no competing interests.
Peer reviewers
Mariana Castells, MD, PhD
Director
Mastocytosis Center and Drug Hypersensitivity and Desensitization Center
Brigham and Women’s Hospital
Professor of Medicine
Harvard Medical School
Boston
MA
Disclosures
MC is the principal investigator for two clinical trials for Blueprint Medicines (using tyrosine kinase inhibitors for indolent systemic mastocytosis); the principal investigator for a Cogent clinical trial for patients with non-advanced clonal mast cell activation disorders. MC is also a consultant for Daiichi Sankyo, the research chair of American Academy of Allergy, Asthma and Immunology Foundation, and director of the American Board of Allergy and Clinical Immunology.
Deepti H Radia, MBBS, MRCPI, FRCPath
Haematology Consultant
Guys and St Thomas’ NHS Foundation Trust
London
UK
Disclosures
DHR has honorary consulting agreements with, and receives educational honoraria/travel support from Blueprint Medicines, Cogent Biosciences and Novartis. DHR is also a member of study steering committees for Blueprint Medicines trials - EXPLORER, PATHFINDER, and Cogent Biosciences trial APEX, and receives research support from Blueprint Medicines.
Differentials
- Somatoform disorders
- Vasovagal reaction
- Carcinoid syndrome
More DifferentialsGuidelines
- Updated diagnostic criteria and classification of mast cell disorders: a consensus proposal
- AAAAI Mast Cell Disorders Committee Work Group Report: mast cell activation syndrome (MCAS) diagnosis and management
More GuidelinesPatient information
Anaphylaxis
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