Bone Tumor Classification

Overview of bone tumour classification systems and key characteristics that distinguish benign from malignant lesions.

Accurate classification of bone tumors is a critical step in determining an effective treatment plan. The WHO introduced the classification of soft tissue and bone tumors (fifth edition) in 2020.

The new WHO classification of soft tissue and bone tumors, introduced in 2020 (fifth edition), has made significant improvements in classification and introduced many new diagnoses.

The basis for the classification of bone tumors is histopathological.

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Bone Tumor Classification

Group	Benign	Intermediate (Local Agressive)	Malignant
Chondrogenic	Subungual exostosis, Periosteal chondroma, Enchondroma, Osteochondroma, Chondroblastoma vb.	Chondromatosis NOS, Atypical cartilaginous tumor	Chondrosarcoma (G1-3), Periosteal, Clear cell, Mesenchymal, Dedifferentiated
Osteogenic	Osteoma NOS, Osteoid osteoma NOS	Osteoblastoma NOS	Low-grade central osteosarcoma, Osteosarcoma NOS, Parosteal, Periosteal, High-grade surface, Secondary
Fibrogenic	—	Desmoplastic fibroma	Fibrosarcoma NOS
Vascular (Bone)	Hemangioma NOS	Epithelioid hemangioma	Epithelioid hemangioendothelioma NOS, Angiosarcoma
Osteoclastic Giant Cell-Rich	Aneurysmal bone cyst, Non-ossifying fibroma	Giant cell tumor of bone NOS	Malignant giant cell tumor of bone
Notochordal	Benign notochordal cell tumor	—	Chordoma NOS (chondroid dahil), Dedifferentiated, Poorly differentiated
Other Mesenchymal (Bone)	Chondromesenchymal hamartoma, Simple bone cyst, Fibrous dysplasia, Osteofibrous dysplasia, Lipoma, Hibernoma	Osteofibrous dysplasia-like adamantinoma, Mesenchymoma NOS	Adamantinoma (dediff.), Leiomyosarcoma NOS, Pleomorphic sarcoma undiff., Bone metastases
Hematopoietic	—	—	Plasmacytoma, Hodgkin, Non-Hodgkin lenfomalar, Langerhans histiocytosis, Erdheim-Chester, Rosai-Dorfman
Undifferentiated Small Round Cell	—	—	Ewing sarcoma, CIC-rearranged, BCOR altered sarcoma