Expanding the Diagnostic Lens: Mast Cell Activation Syndromes and the Hidden Spectrum of Angioedema Associated Mortality in COVID-19.

Recent Developments in the Field of Mast Cell Disorders: Classification, Prognostication, and Management

Expanding Spectrum of Mast Cell Activation Disorders: Monoclonal and Idiopathic Mast Cell Activation Syndromes

Familial hypertryptasemia with associated mast cell activation syndrome

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.

Mast Cell Regulatory Gene Variants Are Common in Mast Cell Activation Syndrome

Mast Cell Diseases in Practice and Research: Issues and Perspectives Raised by Patients and Their Recommendations to the Scientific Community and Beyond

Diagnosis and Management of Patients With Mast Cell Activation Syndromes: Status 2026.

Characterization of Mast Cell Activation Syndrome

Tyrosine kinase inhibitors for the treatment of indolent systemic mastocytosis: Are we there yet?

Dyspareunia, vaginitis and dysfunctional uterine bleeding (DUB) are common problems which, despite their polygenicity, commonly appear idiopathic and treatment-refractory. Mast cell (MC) activation syndrome (MCAS) is a newly-recognised, prevalent, chronic multisystem polymorbidity of general themes of inflammation ± allergic-type phenomena ± aberrant growth/development in assorted tissues. MCs produce significant quantities of heparin, too. As such, MCAS may underlie some cases of chronic dyspareunia, vaginitis or DUB. We report five such patients; all who responded well to MC-targeted treatment. We review aspects of MC biology and pathobiology of potential relevance to otherwise idiopathic persistent inflammatory or coagulopathic genital tract problems. Diagnostic testing for MCAS may be warranted in some patients with chronic dyspareunia, vaginitis or DUB (especially patients whose histories well fit the general profile of MCAS), and prospective therapeutic trials of MC-directed topical and/or systemic therapies may be warranted in such populations. Impact statement What is already known on this subject? Chronic, idiopathic, treatment-refractory female genital tract inflammation or bleeding are common problems for which mast cell (MC) disease, previously generally thought to consist of just rare cases of mastocytosis, and is seldom considered in the differential diagnosis. What do the results of this study add? The substantial prevalence of the newly recognised ‘mast cell activation syndrome’ (MCAS), featuring chronic inappropriate MC activation with little-to-no MC neoplasia, and its clinical presentation with chronic multisystem inflammation ± allergic-type phenomena ± aberrant growth/development in assorted tissues, raises the possibility that MCAS might underlie the aforementioned genital tract problems, especially in patients whose larger clinical presentations fit the MCAS profile. We report five example patients (among many more we have similarly treated) who enjoyed excellent responses to safe, inexpensive MC-targeted treatments, often given just intravaginally. What are the implications of these findings for clinical practice and/or further research? Our report identifies a potentially significant new MC-focused direction, of relevance to millions of affected women worldwide, for clinical treatment as well as for basic and clinical research, which historically has yielded major advancements disappointingly disproportionate to the scope of the affected population.

Mast cell (MC) activation is a key event in allergic reactions, other inflammatory states, and MC activation syndromes. MC-stabilizing agents, mediator-targeting drugs, and drugs interfering with mediator effects are often prescribed for these patients. However, the clinical efficacy of these drugs varies depending on the numbers of involved MCs and the underlying pathology. One straightforward approach would be to eradicate the primary target cell. To date however, no MC-eradicating treatment approach has been developed for patients with MC activation disorders. Nevertheless, recent data suggest that long-term treatment with agents effectively inhibiting KIT function results in the virtual eradication of tissue MCs and a sustained decrease in serum tryptase levels. In many of these patients, MC depletion is associated with a substantial improvement in mediator-induced symptoms. In patients with an underlying KIT D816V-positive mastocytosis, such MC eradication requires an effective inhibitor of KIT D816V, such as avapritinib. However, the use of KIT inhibitors must be balanced against their potential side effects. Here we discuss MC-eradicating strategies in various disease models, the feasibility of this approach, available clinical data, and future prospects for the use of KIT-targeting drugs in MC activation disorders.

Mast cell (MC) activation syndrome (MCAS) is a recently recognized, likely prevalent collection of heterogeneous illnesses of inappropriate MC activation with little to no MC neoplasia likely driven by heterogeneous patterns of constitutively activating mutations in MC regulatory elements including various tyrosine kinases (TKs, dominantly KIT). MCAS typically presents as chronic multisystem polymorbidity of generally inflammatory±allergic theme. As with indolent systemic mastocytosis (SM), treatment of MCAS focuses more against MC mediators than MC neoplasia, but some cases prove refractory even to the TK inhibitor (TKI) imatinib reported useful both in uncommon SM cases not bearing SM's usual imatinib-resistant KIT-D816V mutation and in some cases of MCAS (which rarely bears KIT-D816V). Most allergy is principally a MC activation phenomenon and sunitinib is a multitargeted TKI shown helpful in controlling a murine model of oral allergy syndrome. We present the first report of use of sunitinib in life-threatening MCAS refractory to multiple agents including imatinib achieving immediate, complete, sustained, non-toxic remission suggesting a new option for treatment of aggressive MC disease.

Utility of glucagon-like-peptide-1-receptor agonists in mast cell activation syndrome.

Symptoms of mast cell activation: The patient perspective

Safety of COVID-19 vaccination in patients with clonal mast cell disorders