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Expression of CD2, CD25 and/or CD30 in extracutaneous mast cells (MC) is a minor diagnostic criterion for systemic mastocytosis (SM) in the classification of the World Health Organization and International Consensus Classification. So far, it remains unknown whether expression of these antigens on MC is of prognostic significance in SM. We performed a retrospective multi-center study of patients with SM using the data set of the registry of the European Competence Network on Mastocytosis, including 5034 patients with various MC disorders. The percentage of CD2 - , CD25 + and/or CD30 + MC was considerably lower in patients with indolent SM compared to patients with advanced SM, including aggressive SM and MC leukemia. Whereas CD25 and CD30 expression in MC could not be associated with prognosis, we found that lack of CD2 expression in MC is associated with a significantly reduced overall survival (OS) in patients with SM (p < 0.0001). Lack of CD2 was also associated with the presence of extramedullary involvement affecting the spleen, liver, and/or lymph nodes (odds ratio 2.63 compared to SM with CD2 + MC). Together, lack of CD2 expression in MC is a prognostic marker and indicator of reduced OS and extramedullary disease expansion in patients with SM., Competing Interests: Competing interests: Conflicts of interest declared by the co-autors: Axel Rüfer: Advisory boards: Blueprint Medicines; Oliver Hermine: Research funding support from AB science and Novartis. Advisory board of AB science; Patrizia Bonadonna: Honoraria: Blueprint Medicines; Karin Hartmann: Lectures/consultancy: ALK, Allergopharma, BioCryst, Blueprint Medicines, Cogent, KalVista, Leo, Menarini, Novartis, Pfizer, Sanofi, Takeda, Thermo Fisher; Vito Sabato: Advisory boards: Blueprint Medicines, Cogent, Novartis, Telios. Honoraria: Thermo Fisher; Knut Brockow: Advisory board and honoraria: Blueprint Medicines; Nikolas von Bubnoff: Honoraria Novartis, Takeda, Astra Zeneca, Janssen-Cilag; Paul van Daele: Lectures/consultancy: Novartis, involved in clinical trials for Cogent Biosciences and Blueprint Medicines; Ingunn Dybedal: Advisory board and honoraria: Blueprint Medicines; Chiara Elena: Advisory board and honoraria: Blueprint Medicines, Gilead; Marc Heizmann: Advisory board and honoraria: Novartis; Jens Panse: Advisory board and honoraria: Blueprint Medicines, Novartis, Deciphera; Friederike Wortmann: Advisory board and honoraria: Blueprint Medicines, Novartis, Pierre Fabre, Abbvie; Jason Gotlib: Research Grant (funds for administration of clinical trials): Novartis, Blueprint Medicines, Deciphera, Cogent Biosciences; Advisory Board and Honoraria: Blueprint Medicines, Novartis, Deciphera, Cogent Biosciences; Reimbursement of travel expenses: Novartis, Blueprint Medicines; Andreas Reiter: Honoraria: Novartis, Blueprint Medicines, Incyte, Celgene/Bristol Myers Squibb, AOP Orphan Pharmaceuticals, GlaxoSmithKline, AbbVie; Consulting or Advisory Role: Novartis, Blueprint Medicines, Incyte, Celgene/Bristol Myers Squibb, AOP Orphan Pharmaceuticals, AbbVie; Massimo Triggiani: Advisory Board and Honoraria: Blueprint Medicines, Novartis; Wolfgang R. Sperr: Honoraria from AbbVie, Astellas, Blueprint, BMS-Celgene, Daiichi Sankyo, Deciphera, Incyte, Jazz Pharmaceuticals, Laboratoires Delbert, Novartis, Otsuka, Pfizer, Servier, Stemline, Thermo Fisher; Peter Valent: 1. Advisory board - honoraria: AOP Orphan, Blueprint, Cogent, Delbert, Incyte, Novartis, PentaBase, Pfizer, Stemline. 2. Research grant: AOP Orphan, Pfizer. The remaining co-authors declared no conflict of interest. Ethics approval and consent to participate: All methods were performed in accordance with the relevant guidelines and regulations. The ECNM registry study was approved by the responsible local ethics committee of each participating ECNM center. Written informed consent was obtained from all patients included in the ECNM registry., (© 2025. The Author(s).)

In the current classification of the World Health Organization (WHO), bone marrow mastocytosis (BMM) is a provisional variant of indolent systemic mastocytosis (ISM) defined by bone marrow involvement and absence of skin lesions. However, no additional diagnostic criteria for BMM have been proposed. Within the registry dataset of the European Competence Network on Mastocytosis, we compared characteristics and outcomes of 390 patients with BMM and 1175 patients with typical ISM. BMM patients were significantly older, predominantly male, had lower tryptase and lower burden of neoplastic mast cells, and displayed a higher frequency of allergic reactions, mainly triggered by Hymenoptera, than patients with typical ISM. The estimated 10-year progression-free survival of BMM and typical ISM was 95.9% and 92.6%, respectively. In BMM patients defined by WHO-based criteria, the presence of one B-Finding and tryptase level ≥125 ng/mL were identified as risk factors for progression in multivariate analyses. BMM patients without any of these risk factors were found to have better progression-free survival (p < 0.05) and better overall survival (p < 0.05) than other ISM patients. These data support the proposal to define BMM as a separate SM variant characterized by SM criteria, absence of skin lesions, absence of B-Findings, and tryptase levels <125 ng/mL., (© 2021. The Author(s), under exclusive licence to Springer Nature Limited.)

Mastocytosis is a unique hematologic neoplasm with complex biology and pathology and a variable clinical course. The disease can essentially be divided into cutaneous mastocytosis (CM) and systemic mastocytosis (SM). In adults, SM is diagnosed in most cases and manifests as either indolent or advanced disease. Patients with advanced SM have an unfavorable prognosis with reduced survival. However, so far, little is known about the prevalence of various categories of SM and about prognostic factors. In an attempt to learn more about the behavior and evolution of various forms of CM and SM, the European Competence Network on Mastocytosis (ECNM) initiated a mastocytosis registry in 2012. In this article, the set up and start phase of this registry are described. Until 2018, more than 3000 patients from 12 countries and 25 centers have been enrolled. In a majority of all patients, robust follow-up data and relevant clinical end points are available. Using this data set, a series of registry projects have been launched, with the aim to validate previously identified diagnostic and prognostic variables and to identify new disease-related and patient-related parameters in various forms of mastocytosis. Moreover, the core data set of the registry will be useful to establish multiparametric scoring systems through which prognostication and individualized management of patients with mastocytosis should improve in the foreseeable future., (Copyright © 2019 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

The European Competence Network on Mastocytosis (ECNM) was initiated in 2002 as a multidisciplinary and multinational cooperative approach to increase awareness and to improve diagnosis and therapy of mastocytosis. The network is composed of local centers, physicians, and scientists who have dedicated their work to patients with mastocytosis. A strategic goal of the ECNM is to provide the best available information about the disease to patients and physicians. During the past 10 years, the ECNM has expanded to various countries and contributed successfully to the development of markers, definitions, and standards in the field of mastocytosis. Members of the ECNM organized Annual Meetings in Europe and two Working Conferences on Mastocytosis in Vienna (in 2005 and 2010), and initiated and supported several preclinical and clinical trials. In all these activities, representatives of the ECNM cooperate closely with their US colleagues, with patient-organizations in Europe and in the USA, and with other scientific networks. The ECNM also launched a mastocytosis registry that has been activated in 2012. Using the central database of this registry, cooperative multicenter studies, which should include sufficient numbers of patients and robust evaluations, will be conducted. These studies will increase our knowledge about optimal management and therapy of patients with mastocytosis in the future.

The European Competence Network on Mastocytosis (ECNM) is a Europe-wide, multinational cooperative approach attempting to improve recognition, diagnosis, and therapy of mastocytosis. The network is composed of local centers, physicians, and scientists who have dedicated their work to patients with mastocytosis. However, because of the rarity and complexity of the disease, each single component in the network alone would fail to meet important demands and to reach solid conclusions in this field of applied medicine. The ECNM represents an attempt to overcome this restriction as a cooperative multicenter platform that should serve as an important basis for the development of new therapeutic strategies and diagnostic concepts, and for the standardization of techniques used to determine diagnostic and prognostic parameters. Moreover, using future central databases and registries, a suitable infrastructure for the development of co-operative multicenter clinical trials will be established. In addition, the ECNM is dedicated to provide the best available information about the disease to patients and physicians.