The 2026 World Health Organization Classification of Tumors of Soft Tissue and Bone

The 6th edition of the World Health Organization Classification of Soft Tissue and Bone Tumors (STB6) integrates the latest scientific and molecular discoveries with decades of pathological expertise to establish a globally accepted common language for diagnosis and clinical behavior. In this volume, the “essential” and “desirable” diagnostic criteria have been refined, considering different resource settings, ensuring accuracy while maintaining flexibility. A tumor type (entity) is a tumor in which multiple parameters (eg, clinical, histopathological, and/or genetic features) differ from those of other tumor types. In total, 19 new entities met these criteria and were added. A subtype is different in at least one dimension from the main tumor type (clinical, histopathological, or genetic), preferably resulting in a different treatment or outcome. A morphological pattern (no longer “variant”) is important for pathologists to be aware of to facilitate recognition but is not associated with different clinical behavior. The classification was drafted by 203 editors and authors from 27 countries, representing genetics, medical oncology, surgical oncology, orthopedic surgery, and radiology, in addition to pathology. STB6 includes soft tissue tumors (n=116), bone tumors (n=46), vascular tumors of soft tissue and bone (n=18), undifferentiated spindle and round cell sarcomas (n=4), hematopoietic and dendritic cell neoplasms (n=6), and genetic syndromes (n=6). In total, 62 sarcomas are included. A consensus was reached among the expert editorial board. In this review, we highlight changes in tumor classification in STB6, including recently described tumor types, novel diagnostic markers, recent discoveries in molecular genetics, and improvements in prognostication.

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Publication Details

Journal
The American Journal of Surgical Pathology
Published
2026-10-07
DOI
https://doi.org/10.1097/pas.0000000000002624
Primary Topic
Sarcoma Diagnosis and Treatment
Type
article
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article

The 2026 World Health Organization Classification of Tumors of Soft Tissue and Bone

Meera Hameed, J. L. Bloem, Fikret Dirilenoğlu, Christina Messiou et al.
The American Journal of Surgical Pathology
Sarcoma Diagnosis and Treatment
article

The 2026 World Health Organization Classification of Tumors of Soft Tissue and Bone

Meera Hameed, J. L. Bloem, Fikret Dirilenoğlu, Christina Messiou, Alexander J. Lazar, Jennelle C. Hodge, Judith V. M. G. Bovée, Jason L. Hornick, Cristina R. Antonescu, Nasir Ud Din, Joseph David Khoury, Cyril Fisher, Mertens Fredrik, Markku Miettinen, Pavitratha Puspanathan, Angelo P. Dei Tos, Dilani Lokuhetty, Alessandro Gronchi, Daniel Baumhoer, Christine Giesen, Bharat Rekhi, Akihiko Yoshida, WCT Standing Editorial Board, Jian Wang, G. Petur Nielsen, Harshima Wijesinghe, David Creytens, Yoshinao Oda, Andrew Field, Blanca I. Indave Ruiz, Andrew L. Folpe, Jean-Yves Blay
article en

Abstract

The 6th edition of the World Health Organization Classification of Soft Tissue and Bone Tumors (STB6) integrates the latest scientific and molecular discoveries with decades of pathological expertise to establish a globally accepted common language for diagnosis and clinical behavior. In this volume, the “essential” and “desirable” diagnostic criteria have been refined, considering different resource settings, ensuring accuracy while maintaining flexibility. A tumor type (entity) is a tumor in which multiple parameters (eg, clinical, histopathological, and/or genetic features) differ from those of other tumor types. In total, 19 new entities met these criteria and were added. A subtype is different in at least one dimension from the main tumor type (clinical, histopathological, or genetic), preferably resulting in a different treatment or outcome. A morphological pattern (no longer “variant”) is important for pathologists to be aware of to facilitate recognition but is not associated with different clinical behavior. The classification was drafted by 203 editors and authors from 27 countries, representing genetics, medical oncology, surgical oncology, orthopedic surgery, and radiology, in addition to pathology. STB6 includes soft tissue tumors (n=116), bone tumors (n=46), vascular tumors of soft tissue and bone (n=18), undifferentiated spindle and round cell sarcomas (n=4), hematopoietic and dendritic cell neoplasms (n=6), and genetic syndromes (n=6). In total, 62 sarcomas are included. A consensus was reached among the expert editorial board. In this review, we highlight changes in tumor classification in STB6, including recently described tumor types, novel diagnostic markers, recent discoveries in molecular genetics, and improvements in prognostication.

The American Journal of Surgical Pathology
Université Claude Bernard Lyon 1 (FR), Indiana University Health (US), Brigham and Women's Hospital (US), University Hospitals Birmingham NHS Foundation Trust (GB), Mayo Clinic (US), Memorial Sloan Kettering Cancer Center (US), The University of Texas MD Anderson Cancer Center (US), Kyushu University (JP), Harvard University (US), University of Padua (IT), Lund University (SE), Homi Bhabha National Institute (IN), Fudan University (CN), Leiden University Medical Center (NL), Ghent University Hospital (BE), Research Foundation - Flanders (BE), Aga Khan University Hospital (PK), The Netherlands Cancer Institute (NL), Ghent University (BE), St Vincent's Hospital Sydney (AU), National Cancer Centre Japan (JP), Massachusetts General Hospital (US), Fudan University Shanghai Cancer Center (CN), St Vincent’s Private Hospital Sydney (AU), Centre Léon Bérard (FR), Cancer Research Institute Ghent (BE), Royal Marsden Hospital (GB), OST - Ostschweizer Fachhochschule (CH), National Cancer Institute (US), Fondazione IRCCS Istituto Nazionale dei Tumori (IT), Ostschweizer Kinderspital (CH), Centre international de recherche sur le cancer (FR), Indiana University – Purdue University Indianapolis (US), University of Nebraska Medical Center (US), The University of Notre Dame Australia (AU)
Openalex Percentile: Top 12%
Sarcoma Diagnosis and Treatment
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