The World Health Organization (WHO) classification of bone tumors is the most widely used pathologic classification system for such disorders. The 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 tumors
central atypical cartilaginous tumor / chondrosarcoma (grade 1)
secondary peripheral atypical cartilaginous tumor / chondrosarcoma (grade 1)
central chondrosarcoma (grades 2-3)
secondary chondrosarcoma (grade 2-3)
Osteogenic tumors
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conventional osteosarcoma
Fibrogenic tumors
Vascular tumors
Osteoclastic giant cell-rich tumors
Notochordal tumors
Other mesenchymal tumors of bone
lipoma of bone
Hematopoietic neoplasms
Changes from the prior version
Entities and variants
Entities include the following 1:
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chondrogenic tumors
secondary peripheral atypical cartilaginous tumor / chondrosarcoma (grade 1)
secondary chondrosarcoma (grade 2-3)
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osteogenic tumors
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notochordal tumors
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other mesenchymal tumors of bone
Other changes
Ewing sarcoma has been moved to a whole different chapter together with several other 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 tumor / chondrosarcoma (grade 1)
secondary peripheral atypical cartilaginous tumor / 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 tumors
Langerhans cell histiocytosis, Erdheim-Chester disease and Rosai-Dorfman disease have been classified as hematopoietic neoplasms of bone
myogenic, lipogenic, epithelial tumors and tumors of undefined neoplastic nature have been classified as other mesenchymal tumors of bone which also includes undifferentiated pleomorphic sarcoma
giant cell lesion of the small bones has been removed as a separate entity