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Systemic Mastocytosis in 910 Patients: Prognostic Contribution of the International Consensus Classification in the Context of the Mayo Alliance Prognostic System

  • 0Division of Hematology, Mayo Clinic, Rochester, Minnesota, USA.
American Journal of Hematology +

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July 3, 2025

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July 3, 2025

View abstract on PubMed

Summary

This summary is machine-generated.

The International Consensus Classification (ICC) for systemic mastocytosis (SM) offers more accurate prognostic predictions than the WHO-HAEM5 system. ICC classification improves risk stratification by integrating clinical, morphological, and molecular factors for better patient outcomes.

Area Of Science

  • Hematology
  • Oncology
  • Pathology

Background

  • Systemic mastocytosis (SM) is a rare hematologic neoplasm with variable clinical courses.
  • Accurate prognostic classification is crucial for guiding treatment and predicting patient outcomes.
  • Existing classifications, such as the World Health Organization-Haematopoietic and lymphoid tissues, fifth edition (WHO-HAEM5), have limitations in prognostic accuracy.

Purpose Of The Study

  • To evaluate the prognostic contribution of the International Consensus Classification (ICC) for SM.
  • To compare the prognostic performance of ICC with the WHO-HAEM5 classification.
  • To assess the combined prognostic value of ICC and the Mayo Alliance Prognostic System (MAPS) for SM.

Main Methods

  • Retrospective analysis of 910 patients with SM seen at the Mayo Clinic (1968-2024).
  • Categorization of patients based on WHO-HAEM5 and ICC subcategories, including indolent/smoldering SM (ISM/SSM), SM associated with another hematological neoplasm (SM-AHN), SM associated with another myeloid neoplasm (SM-AMN), SM associated with lymphoid neoplasm (SM-ALN), and mast cell leukemia (MCL).
  • Multivariable analysis incorporating clinical variables (age, anemia, alkaline phosphatase, platelet count) and molecular data (ASXL1, SRSF2, NRAS mutations).

Main Results

  • ICC-defined MCL showed significantly shorter overall survival (OS) compared to SM-AMN (0.08 vs. 2.0 years, p < 0.01).
  • ICC-defined SM-AMN had significantly shorter OS than SM-ALN (2.0 vs. 8.1 years, p < 0.01).
  • Multivariable analysis confirmed ICC subcategories and MAPS risk variables (age, anemia, alkaline phosphatase, platelet count) as independent prognostic factors.
  • Inclusion of mutational data identified ASXL1, SRSF2, and NRAS mutations as significant risk factors, replacing anemia in the model.

Conclusions

  • The International Consensus Classification (ICC) provides a more prognostically accurate framework for systemic mastocytosis compared to WHO-HAEM5.
  • ICC enhances the prognostic value of morphology in SM risk models.
  • Integrating ICC subcategories with clinical and molecular data, including specific mutations, improves risk stratification and prediction of outcomes in SM.

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