Osteosarcoma
Epidemiology and
Etiology:
- <20y
predominantly
- bimodal
distribution – 2nd decade and >60y
- risk
factors:
- Paget
disease
- Radiation
exposure
- Bone
infarction
- Fibrous
dysplasia
- Chronic
osteomyelitis
- Genetic
syndromes
- Primary
(most common):
- Underlying
bone is unremarkable
- Secondary:
- Underlying
bone with disease (as above)
Common sites:
- long
bones of the extremities (80% of young, 50% of old)
- metaphysic
(most common)
- particularly
knee
- craniofacial
bones (20% of old)
- spine
- pelvis
(20% of old)
- mets
- lung
(10-20% at presentation)
- bone
- brain
- others
Gross features:
- bulky
- gritty
- gray-white
- hemorrhagic
areas
- cystic
degeneration
- destroying
surrounding cortices frequently
- soft
tissue mass component frequently
- extensive
medullary spread
- infrequently
penetrate the epiphyseal plate
- infrequently
involve the joint
- radiology:
- large
- destructive
- mixed
lytic and blastic
- permeative margins
- lifting
periosteum frequently (Codman triangle)
- oral
site:
- classic
opaque “sunburst” pattern sometimes
- subtypes
depending on which part of bone involved
- intramedullary (most common)
- intracortical
- surface
- solitary
(most common)
- multicentric maybe
-
Histologic
features:
- Cells
vary in size and shape
- Large hyperchromatic nuclei frequently
- Bizarre
tumour giant cells commonly
- Mitoses
common
- Bone
formation
- Osteoid or woven bone
surrounded by and containing malignant cells
- Coarse,
lacelike architecture
- Or
broad sheets, primitive trabeculae
- Other
matrices may be present:
- Necrosis
often
- Vascular
invasion conspicuous usually
- Subtypes
depending on degree of differentiation
- Poorly
differentiated most common
- Osteoblastic variant
- Chondroblastic variant
- Abundant
cartilage matrix
- Fibroblastic
variant
- Telangiectatic variant
- Small
cell variant
- Giant
cell variant
-
Immunophenotype:
Marker:
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Sensitivity:
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Specificity:
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Molecular features:
- RB
defects (60-70% of sporadic)
- Cell
cycle gene abnormalities:
- p53
- CDK4
- p16
- INK4A
- CYCLIN
D1
- MDM2
Other features:
- clinical
features (bone tumours):
- pain
is first and most common
- pathological
fracture
- swelling
- joint
limitation
- Response
to treatment is important prognostic factor:
- % of tumour that is necrotic or fibrotic or granulation
tissue
- Gross
impression (confirm gross appearance with representative sections)
- 90%
is favorable prognosis
- Oral osteosarcoma: prognosis more favorable than other
sites
References: