Bone tumors
A. Primary bone tumors arise from bone or bone-derived cells and tissues; they can
be benign or malignant.
B. Secondary bone tumors arise from tumors metastasizing to bones; always
malignant.
Classification (WHO)
1. Chondrogenic tumors
- Enchondroma
- Osteochondroma
- Periosteal chondrosarcoma
2. Osteogenic tumors
- Osteoma
- Osteoid osteoma
- Osteoblastoma
- Conventional osteosarcoma
- Secondary osteosarcoma
3. Fibrogenic tumors
- Fibrosarcoma
4. Vascular tumors
- Hemangioma
- Angiosarcoma
5. Osteoclastic giant cell-rich tumors
- Giant cell tumor of bone
6. Notochordal tumors
- Chordoma
7. Other mesenchymal tumors
- Bone metastasis
8. Hematopoietic neoplasms
- Erdheim-Chester disease, Langerhans cell histiocytosis
- DLBCL, Follicular lymphoma, T-cell lymphoma, Burkitt lymphoma, Hodgkin and
Non-Hodgkin lymphoma
Diagnosis of hard tissue neoplasms requires integration of both pathological and
radiological findings. Typical margins in bone lesions:
- IA: sclerotic - tissue outside lesion resists lesion itself e.g. non-ossifying fibroma,
that is usually exclusively diagnosed radiologically (no pathology needed).
- IB: non-sclerotic – well-defined margins, lesion slightly more aggressive e.g.
enchondroma (cartilage producing benign neoplasm).
- IC: ill-defined – no clear margin between lesion and healthy tissue e.g. multiple
myeloma (usually in axial skeleton)
- II: moth-eaten – aggressive disease with irregular areas of osteolysis, e.g.
osteosarcoma.
- III: permeative – very aggressive, e.g. chondrosarcoma.
, Additionally, in aggressive hard tissue neoplasms, you may also observe periosteal
reactions: Codman triangle e.g. in osteochondroma is due to continuous new bone
formation by the periosteum when bone breaks, and onion-skinning is frequently found
in chondrosarcoma, or spiculated margins.
Primary bone tumors
Most bone tumors, especially in children and young adults (age <30) are benign and have
excellent prognosis with or without curative surgical excision. Benign neoplasms are
often asymptomatic incidental findings but they may produce pain or be found in case of
pathological fracture. The most common ones are:
- Osteochondromas: in individuals aged 10-20.
- Osteoblastomas: in children and adolescents
- Osteoid osteomas: in adolescents
Malignant primary bone tumors are exceedingly rare and are more common in older
adults. Most common types:
- Osteosarcomas
- Chondrosarcomas
- Bone marrow tumors
Grading is histotype-determined
(similar to CNS tumors), based on
similarity to normal adult bone tissue
or matrix produced and on biological
behavior, so neoplasms are
categorized as benign, intermediate
(locally aggressive or rarely
metastasizing), and malignant. The
only exception is chondrosarcoma that can be graded based on its specific features.
Conventional osteosarcomas are high grade by nature.
Remember that each specific bone tumor has a predilection for:
- a particular age group:
o the most common bone neoplasms in
young age are osteosarcoma and Ewing
sarcoma
o the most common bone tumors in adults
are chondrosarcoma, chordoma
(notochordal tumors arising from the axial
skeleton, at cranial base or sacrum) and
undifferentiated pleomorphic sarcoma.
- a specific anatomical site of the bone: Ewing
sarcomas and chondrosarcomas tend to occur at
the diaphysis whilst osteosarcomas in children
and young adolescents usually occur in the
metaphyseal area of long bones like the tibia.
A. Primary bone tumors arise from bone or bone-derived cells and tissues; they can
be benign or malignant.
B. Secondary bone tumors arise from tumors metastasizing to bones; always
malignant.
Classification (WHO)
1. Chondrogenic tumors
- Enchondroma
- Osteochondroma
- Periosteal chondrosarcoma
2. Osteogenic tumors
- Osteoma
- Osteoid osteoma
- Osteoblastoma
- Conventional osteosarcoma
- Secondary osteosarcoma
3. Fibrogenic tumors
- Fibrosarcoma
4. Vascular tumors
- Hemangioma
- Angiosarcoma
5. Osteoclastic giant cell-rich tumors
- Giant cell tumor of bone
6. Notochordal tumors
- Chordoma
7. Other mesenchymal tumors
- Bone metastasis
8. Hematopoietic neoplasms
- Erdheim-Chester disease, Langerhans cell histiocytosis
- DLBCL, Follicular lymphoma, T-cell lymphoma, Burkitt lymphoma, Hodgkin and
Non-Hodgkin lymphoma
Diagnosis of hard tissue neoplasms requires integration of both pathological and
radiological findings. Typical margins in bone lesions:
- IA: sclerotic - tissue outside lesion resists lesion itself e.g. non-ossifying fibroma,
that is usually exclusively diagnosed radiologically (no pathology needed).
- IB: non-sclerotic – well-defined margins, lesion slightly more aggressive e.g.
enchondroma (cartilage producing benign neoplasm).
- IC: ill-defined – no clear margin between lesion and healthy tissue e.g. multiple
myeloma (usually in axial skeleton)
- II: moth-eaten – aggressive disease with irregular areas of osteolysis, e.g.
osteosarcoma.
- III: permeative – very aggressive, e.g. chondrosarcoma.
, Additionally, in aggressive hard tissue neoplasms, you may also observe periosteal
reactions: Codman triangle e.g. in osteochondroma is due to continuous new bone
formation by the periosteum when bone breaks, and onion-skinning is frequently found
in chondrosarcoma, or spiculated margins.
Primary bone tumors
Most bone tumors, especially in children and young adults (age <30) are benign and have
excellent prognosis with or without curative surgical excision. Benign neoplasms are
often asymptomatic incidental findings but they may produce pain or be found in case of
pathological fracture. The most common ones are:
- Osteochondromas: in individuals aged 10-20.
- Osteoblastomas: in children and adolescents
- Osteoid osteomas: in adolescents
Malignant primary bone tumors are exceedingly rare and are more common in older
adults. Most common types:
- Osteosarcomas
- Chondrosarcomas
- Bone marrow tumors
Grading is histotype-determined
(similar to CNS tumors), based on
similarity to normal adult bone tissue
or matrix produced and on biological
behavior, so neoplasms are
categorized as benign, intermediate
(locally aggressive or rarely
metastasizing), and malignant. The
only exception is chondrosarcoma that can be graded based on its specific features.
Conventional osteosarcomas are high grade by nature.
Remember that each specific bone tumor has a predilection for:
- a particular age group:
o the most common bone neoplasms in
young age are osteosarcoma and Ewing
sarcoma
o the most common bone tumors in adults
are chondrosarcoma, chordoma
(notochordal tumors arising from the axial
skeleton, at cranial base or sacrum) and
undifferentiated pleomorphic sarcoma.
- a specific anatomical site of the bone: Ewing
sarcomas and chondrosarcomas tend to occur at
the diaphysis whilst osteosarcomas in children
and young adolescents usually occur in the
metaphyseal area of long bones like the tibia.
