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Clinical Approach to Mast Cell Activation Syndrome: A Practical Overview

Matito A1, Escribese MM2, Longo N3, Mayorga C4, Luengo-Sánchez O5, Pérez-Gordo M6, Matheu V7, Labrador-Horrillo M5, Pascal M8, Seoane-Reula ME9, on behalf of the Comité de Inmunología de la Sociedad Española de Alergología e Inmunología Clínica (SEAIC)

1Instituto de Estudios de Mastocitosis de Castilla La Mancha (CLMast), Hospital Virgen del Valle, Toledo, Spain
2Department of Basic Medical Sciences, Faculty of Medicine, San Pablo CEU University, Madrid, Spain
3Allergy Department, Hospital Universitario de Araba, Osakidetza, Vitoria, Spain
4Allergy Research Group, Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga-IBIMA, ARADyAL, Málaga, Spain
5Allergy Department, Vall d’Hebron Hospital Universitari, Vall d’Hebron Institut de Recerca (VHIR), Universitat Autònoma de Barcelona (UAB), ARADyAL research network, Instituto de Salud Carlos III (ISCIII), Barcelona, Spain
6Basic Medical Science Department, Faculty of Medicine, CEU San Pablo University, ARADyAL, Madrid, Spain
7IDP and Allergy Department, Hospital Universitario de Canarias, Tenerife, Spain
8Immunology Department, CDB, Hospital Clínic de Barcelona; IDIBAPS, Universitat de Barcelona; ARADyAL research network, Instituto de Salud Carlos III (ISCIII), Barcelona, Spain
9Pediatric Allergy and Immunology Unit, Hospital General Universitario Gregorio Marañón, Madrid, Spain

J Investig Allergol Clin Immunol 2021; Vol 31(6) : 461-470
doi: 10.18176/jiaci.0675

The diagnosis of mast cell activation syndrome (MCAS) is defined by 3 criteria: (1) typical clinical signs and symptoms of acute, recurrent (episodic), and systemic mast cell activation (MCA); (2) increase in tryptase level to >20% + 2 ng/mL within 1-4 hours after onset of the acute crisis; and (3) response of MCA symptoms to antimediator therapy. Classification of MCAS requires highly sensitive and specific methodological approaches for the assessment of clonal bone marrow mast cells at low frequencies. The Spanish Network on Mastocytosis score has been used successfully as a predictive model for selecting MCAS candidates for bone marrow studies based on a high probability of an underlying clonal mast cell disorder. In this article, we propose a diagnostic algorithm and focus on the practical evaluation and management of patients with suspected MCAS.

Key words: Anaphylaxis, Antimediator therapy, Mast cell activation syndrome, Mast cell mediator release–related symptoms, Tryptase