The World Health Organisation (WHO) classification of bone tumours is the most widely used pathologic classification system for such disorders. The current revision, part of the 5th edition of the WHO series, was published in 2020 and is reflected in the article below 1.
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Classification
Chondrogenic tumours
central atypical cartilaginous tumour / chondrosarcoma (grade 1)
secondary peripheral atypical cartilaginous tumour / chondrosarcoma (grade 1)
central chondrosarcoma (grades 2-3)
secondary chondrosarcoma (grade 2-3)
Osteogenic tumours
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conventional osteosarcoma
Fibrogenic tumours
Vascular tumours
Osteoclastic giant cell-rich tumours
Notochordal tumours
Other mesenchymal tumours of bone
lipoma of bone
Haematopoietic neoplasms
Changes from the prior version
New entities and variants
Newly introduced entities include the following 1:
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chondrogenic tumours
secondary peripheral atypical cartilaginous tumour / chondrosarcoma (grade 1)
secondary chondrosarcoma (grade 2-3)
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osteogenic tumours
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notochordal tumours
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other mesenchymal tumours of bone
Other changes
Ewing sarcoma has been moved to a whole different chapter together with several other new entities of undifferentiated small round cell sarcomas of soft tissue and bone
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clearer differentiation of central and secondary peripheral chondrosarcoma variants:
central atypical cartilaginous tumour / chondrosarcoma (grade 1)
secondary peripheral atypical cartilaginous tumour / chondrosarcoma (grade 1)
central chondrosarcoma (grades 2-3)
secondary chondrosarcoma (grade 2-3)
non-ossifying fibroma and aneurysmal bone cyst have been classified as osteoclastic giant cell-rich tumours
Langerhans cell histiocytosis, Erdheim-Chester disease and Rosai-Dorfman disease have been classified as haematopoietic neoplasms of bone
myogenic, lipogenic, epithelial tumours and tumours of undefined neoplastic nature have been classified as other mesenchymal tumours of bone which also includes undifferentiated pleomorphic sarcoma
giant cell lesion of the small bones has been removed as a separate entity