Global Classification of Mast Cell Activation Disorders: An ICD-10-CM–Adjusted Proposal of the ECNM-AIM Consortium

Peter Valent, Karin Hartmann, Patrizia Bonadonna, Theo Gülen, Knut Brockow, Ivan Alvarez-Twose, Olivier Hermine, Marek Niedoszytko, Melody C. Carter, Gregor Hoermann, Joseph H. Butterfield, Jonathan J. Lyons, Wolfgang R. Sperr, Georg Greiner, Karl Sotlar, Hanneke C. Kluin-Nelemans, Juliana Schwaab, Magdalena Lange, Tracy I. George, Frank SiebenhaarSigurd Broesby-Olsen, Mohamad Jawhar, Boguslaw Nedoszytko, Mariana Castells, Alberto Orfao, Jason Gotlib, Andreas Reiter, Hans Peter Horny, Massimo Triggiani, Michel Arock, Dean D. Metcalfe, Cem Akin

Research output: Contribution to journalArticlepeer-review

33 Scopus citations


Mast cell activation (MCA) is common and occurs in a number of pathologic conditions, including IgE-dependent and independent allergic reactions, atopic disorders, autoimmune processes, and mastocytosis. In a subset of patients, no underlying disease and no known trigger of MCA are found. When the symptoms are severe, systemic, and recurrent, and accompanied by a diagnostic increase in the serum tryptase level or other mast cell mediators, an MCA syndrome (MCAS) may be diagnosed. In these patients, the symptoms typically respond to drugs suppressing MCA, mediator production in mast cells, or mediator effects. In each case, diagnostic consensus criteria must be fulfilled to diagnose MCAS. In other patients, MCA may be local, less severe, or less acute, or may be suspected but not confirmed, so that the diagnostic criteria of MCAS are not fulfilled. In these patients, it may be difficult to prove MCA, for example, by measuring multiple mast cell mediators or basophil activation, the latter as a surrogate of IgE-dependent hypersensitivity. However, validated diagnostic criteria for implicating suspected MCA behind such conditions are lacking, even if some of these conditions have recently been assigned to an International Classification of Diseases-10-Clinical Modification code (ICD-10-CM). In this article, we discuss diagnostic features and criteria and propose a ICD-10-CM–adjusted classification for disorders associated with MCA, herein referred to as MCA disorders (MCADs), with special emphasis on the delineation between confirmed MCAS, MCAD not fulfilling MCAS criteria, and suspected MCAD that is not present. In addition, we discuss the discrimination between overt MCAD and predisposing conditions, such as atopic states, mastocytosis, and hereditary alpha tryptasemia.

Original languageEnglish
Pages (from-to)1941-1950
Number of pages10
JournalJournal of Allergy and Clinical Immunology: In Practice
Issue number8
StatePublished - Aug 2022


  • Diagnostic criteria
  • HαT
  • MCAS
  • Mast cell activation
  • Mastocytosis


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