Outcomes and prognostic factors in patients with systemic mastocytosis and an associated myeloid neoplasm: an international ECNM registry study

BACKGROUND: Systemic mastocytosis (SM) is a spectrum of hematologic disorders characterized by accumulation of atypical mast cells (MCs) in extracutaneous organs. SM with an associated hematologic neoplasm (SM-AHN), the most frequent subtype of advanced SM, is predominantly associated with myeloid neoplasms, consistent with shared clonal architecture. Because of its rarity and heterogeneity, robust outcome data aligned with contemporary classifications are needed to inform risk stratification. METHODS: We analyzed the 10th data wave of the European Competence Network on Mastocytosis registry (34 European centers and 1 US center). SM and AHN diagnoses followed the 2022 World Health Organization classification. Baseline characteristics and overall survival (OS) were compared between patients with myeloid SM-AHN and SM without AHN (SM-no-AHN). Within SM-AHN, outcomes were analyzed by SM component (advanced: aggressive SM [ASM] or MC leukemia [MCL] vs. non-advanced: bone marrow mastocytosis, indolent SM, or smoldering SM) and AHN subtype. RESULTS: Among 3,925 patients with SM, 467 (11.9%) had myeloid SM-AHN. Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) were the most frequent AHN category (41.1%), with chronic myelomonocytic leukemia as the most common subtype (29.6%). Compared with SM-no-AHN, SM-AHN patients were older, more often male, and less frequently had skin involvement. The SM component was advanced in 55.0% of SM-AHN versus 5.8% of SM-no-AHN (p < 0.001). OS was shorter in SM-AHN than SM-no-AHN (median 36.1 vs. 340.9 months; p < 0.001) and was reduced across SM subtypes, including ASM (31.0 vs. 81.1 months) and MCL (7.1 vs. 23.2 months). Within SM-AHN, advanced SM-AHN had shorter OS than non-advanced SM-AHN (28.3 vs. 70.9 months; p < 0.001). Median OS differed by AHN subtype (57.0 months in SM-MPN, 35.7 in SM-MDS, 34.2 in SM-MDS/MPN, and 14.7 in SM associated with acute myeloid leukemia; p < 0.001). In multivariable analysis, non-advanced SM (vs. advanced) remained independently associated with improved OS (hazard ratio = 0.44; p < 0.001). CONCLUSIONS: SM-AHN is associated with reduced survival compared with SM without AHN across SM subtypes. Outcomes in SM-AHN are driven primarily by the aggressiveness of the mastocytosis component, supporting recognition and classification of SM in patients with concomitant myeloid neoplasms, given approved KIT-targeted tyrosine kinase inhibitors for advanced SM.

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Journal
Journal of Hematology & Oncology
Published
2026-06-26
DOI
https://doi.org/10.1186/s13045-026-01819-1
Primary Topic
Mast cells and histamine
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article
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article

Outcomes and prognostic factors in patients with systemic mastocytosis and an associated myeloid neoplasm: an international ECNM registry study

Maël Heiblig, Peter Valent, Akif Selim Yavuz, Deborah Christen et al.
Journal of Hematology & Oncology
Mast cells and histamine
article

Outcomes and prognostic factors in patients with systemic mastocytosis and an associated myeloid neoplasm: an international ECNM registry study

Maël Heiblig, Peter Valent, Akif Selim Yavuz, Deborah Christen, Sophie Dimicoli‐Salazar, Mattias Mattsson, Irena Angelova‐Fischer, Martina Sperr, Marc Heizmann, Friederike Wortmann, Horia Bumbea, A Reiter, Michael Doubek, Hanneke C. Kluin‐Nelemans, Anna Belloni Fortina, Axel Rüfer, Olivier Tournilhac, Simge Erdem, Khalid Shoumariyeh, Theo Gülen, Johannes Lübke, Mariarita Sciumé, Olivier Hermine, Delia Soare, S Barete, Massimiliano Bonifacio, Ingunn Dybedal, Luca Malcovati, Roberta Parente, C. Gourguechon, Valentina Bellani, Orianne Debeaupuis, Laurent Frenzel, Nicole Nojarov, Daniel Baffoe, J N Oude Elberink, Alex Stefan, Judit Várkonyi, Stephan de Bra, P. Pyatilova, C Bulai Livideanu, Tobias Michael Franz, Marek Niedoszytko, N Von Bubnoff, Ilaria Tanasi, Juliana Schwaab, Jens Panse, Julien Rossignol, Michel Arock, Jason Gotlib, Johannes N. Woltsche, Gandhi Damaj, Karin Hartmann, Chiara Elena, Aleksandra Gorska, Madlen Jentzsch, Michael Makris, Knut Brockow, Christine Breynaert, Saskia K. Klein, Sotirios Papageorgiou, Andrzej Mital, Wolfgang R. Sperr, Paul van Daele, Vito Sabato, Olivier Lortholary, Massimo Triggiani, Frank Siebenhaar
article en

Abstract

BACKGROUND: Systemic mastocytosis (SM) is a spectrum of hematologic disorders characterized by accumulation of atypical mast cells (MCs) in extracutaneous organs. SM with an associated hematologic neoplasm (SM-AHN), the most frequent subtype of advanced SM, is predominantly associated with myeloid neoplasms, consistent with shared clonal architecture. Because of its rarity and heterogeneity, robust outcome data aligned with contemporary classifications are needed to inform risk stratification. METHODS: We analyzed the 10th data wave of the European Competence Network on Mastocytosis registry (34 European centers and 1 US center). SM and AHN diagnoses followed the 2022 World Health Organization classification. Baseline characteristics and overall survival (OS) were compared between patients with myeloid SM-AHN and SM without AHN (SM-no-AHN). Within SM-AHN, outcomes were analyzed by SM component (advanced: aggressive SM [ASM] or MC leukemia [MCL] vs. non-advanced: bone marrow mastocytosis, indolent SM, or smoldering SM) and AHN subtype. RESULTS: Among 3,925 patients with SM, 467 (11.9%) had myeloid SM-AHN. Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) were the most frequent AHN category (41.1%), with chronic myelomonocytic leukemia as the most common subtype (29.6%). Compared with SM-no-AHN, SM-AHN patients were older, more often male, and less frequently had skin involvement. The SM component was advanced in 55.0% of SM-AHN versus 5.8% of SM-no-AHN (p < 0.001). OS was shorter in SM-AHN than SM-no-AHN (median 36.1 vs. 340.9 months; p < 0.001) and was reduced across SM subtypes, including ASM (31.0 vs. 81.1 months) and MCL (7.1 vs. 23.2 months). Within SM-AHN, advanced SM-AHN had shorter OS than non-advanced SM-AHN (28.3 vs. 70.9 months; p < 0.001). Median OS differed by AHN subtype (57.0 months in SM-MPN, 35.7 in SM-MDS, 34.2 in SM-MDS/MPN, and 14.7 in SM associated with acute myeloid leukemia; p < 0.001). In multivariable analysis, non-advanced SM (vs. advanced) remained independently associated with improved OS (hazard ratio = 0.44; p < 0.001). CONCLUSIONS: SM-AHN is associated with reduced survival compared with SM without AHN across SM subtypes. Outcomes in SM-AHN are driven primarily by the aggressiveness of the mastocytosis component, supporting recognition and classification of SM in patients with concomitant myeloid neoplasms, given approved KIT-targeted tyrosine kinase inhibitors for advanced SM.

Journal of Hematology & Oncology
Semmelweis University (HU), Oslo University Hospital (NO), Centre National de la Recherche Scientifique (FR), University of Salerno (IT), University Medical Center Groningen (NL), Karolinska University Hospital (SE), Uppsala University Hospital (SE), University of Padua (IT), University of Antwerp (BE), Inserm (FR), University of Freiburg (DE), Carol Davila University of Medicine and Pharmacy (RO), University of Groningen (NL), National and Kapodistrian University of Athens (GR), Medical University of Graz (AT), Université Paris Cité (FR), Masaryk University (CZ), Heidelberg University (DE), Rega Institute for Medical Research (BE), University of Pavia (IT), University Hospital Heidelberg (DE), University Hospital of Basel (CH), Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico (IT), Karolinska Institutet (SE), Centre Hospitalier Universitaire de Bordeaux (FR), Centre Hospitalier Universitaire de Toulouse (FR), Humboldt-Universität zu Berlin (DE), Sorbonne Université (FR), Institut Necker Enfants Malades (FR), Hôpital Cochin (FR), Azienda Ospedaliera Universitaria Integrata Verona (IT), Centre Hospitalier Universitaire Amiens-Picardie (FR), Assistance Publique – Hôpitaux de Paris (FR), Universitäres Kinderwunschzentrum Lübeck (DE), Emergency University (US), Antwerp University Hospital (BE), University of Clermont Auvergne (FR), Institut de Biologie Paris-Seine (FR), Fraunhofer Institute for Translational Medicine and Pharmacology (DE), University Hospital Schleswig-Holstein (DE), Hôpital Lyon Sud (FR), Kepler Universitätsklinikum (AT), Luzerner Kantonsspital (CH), Pitié-Salpêtrière Hospital (FR), University Hospital Leipzig (DE), Centre Hospitalier Universitaire de Clermont-Ferrand (FR), University General Hospital Attikon (GR), Ludwig Boltzmann Institute Applied Diagnostics (AT), Azienda Ospedale - Università Padova (IT), Ludwig Boltzmann Institute for Cancer Research (AT), Policlinico San Matteo Fondazione (IT), Istituti di Ricovero e Cura a Carattere Scientifico (IT), Institut Alfred Fournier (FR), Kantonsspital Aarau (CH), Institut des Maladies Génétiques Imagine (FR), Technical University of Munich (DE), Istanbul University (TR), Gdańsk Medical University (PL), Freie Universität Berlin (DE), Medical University of Vienna (AT), Charité - Universitätsmedizin Berlin (DE), Institut Curie (FR), RWTH Aachen University (DE), Erasmus University Rotterdam (NL), University of Lübeck (DE), Stanford University (US), KU Leuven (BE)
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