The sixth edition of the WHO Classification of Soft Tissue and Bone Tumours was written by 203 editors and authors from 27 countries spanning pathology, genetics, medical and surgical oncology, orthopaedics and radiology. A consensus was reached among the editorial board.
The volume lists 116 soft tissue tumours, 46 bone tumours, 18 vascular tumours of soft tissue and bone, 4 undifferentiated spindle and round cell sarcomas, 6 haematopoietic and dendritic cell neoplasms and 6 genetic syndromes, with 62 sarcomas in total. Nineteen new entities were added. An entity differs from others in several parameters; a subtype differs in at least one dimension, ideally with a different treatment or outcome. A morphological pattern, no longer called a variant, is worth recognising but is not linked to different clinical behaviour.
Essential and desirable diagnostic criteria were refined with different resource settings in mind. For a laboratory, the immediate work is to see which new entities and markers apply to its case mix and which molecular tests it needs to access or refer out.
- Nineteen new entities were added to the classification.
- 'Variant' is now 'morphological pattern' when behaviour does not differ.
- Essential and desirable criteria were adjusted to resource setting, which helps laboratories with limited molecular access.
- Review reporting templates and referral pathways for newly defined entities.
- Use the full volume, not this overview, when changing diagnostic practice.
Why it matters
Diagnostic names and criteria in sarcoma drive treatment and trial eligibility, so wording changes reach clinicians.
Don't overread it
This is an overview of a classification produced by consensus, not a study showing improved outcomes.
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