1. Pattern of bone destruction
Geographic
Least aggressive
- usually indicative of slow growing lesion
- usually seen in benign tumours
- may be myeloma / mets / OM
Narrow transition from normal to abnormal bone
- Margin of the lesion is well defined
- margin is easily separated from surrounding bone
- margin may be smooth / irregular, sclerotic / non sclerotic
Moth-eaten
More aggressive
- characteristic of more rapidly growing lesion
- seen in malignant bone tumours & osteomyelitis
Wider zone of transition from normal to abnormal
- less well defined lesional margin
Permeative
Aggressive bone lesion with rapid growth potential
- malignant tumours such as Ewing's
Wide zone of transition
- lesion is poorly demarcated
- not easily separated from surrounding N bone
2. Size
In general 1° malignant tumours are larger than benign tumours
- may be >5cm when first discovered
3. Growth rate
Benign lesions grow slowly or not at all
- plasma cell cytomas may occas be slow
- benign tumours occas are fast
Slowly growing lesions can have associated sclerotic reactive margin
4. Visible tumour matrix
Calcification
- usually central
- may be ring-like, flocculent, fleck-like
DDx
- chondromas, chondroblastoma, chondrosarcoma, chondromyxoid fibroma
- synovial sarcoma
- occasionally seen in ewings (rare)
- hemangioma
Neoplastic Bone
- osteosarcomas, ossifying fibromas, osteomas, osteoblastomas
Ground Glass
- fibrous dysplasia
5. Cortical erosion
If lesion erodes endosteal surface
- new bone tends to be laid down on periosteal surface and the bone widens
Non aggressive
- may not provoke an endosteal reaction
Enchondroma / chondrosarcoma
- can lead to endosteal scalloping & new periosteal bone may be laid down
ABC
- can expand the cortex rapidly
Malignant tumours
- can expand through cortex and lift periosteum
6. Periosteal response
Periosteal reaction
- slow growing tumour can evoke a periosteal response
- can get buttress at junction of normal & expanded bone
Onion skin pattern
- Ewing's
- multiple layers of periosteal new bone formation
Codman's triangle
- OS, Ewing's, infection
- lifting of periosteum at edge of lesion with bone formation
Sunburst pattern
- OS
- rays of periosteal bone formation radiating away from the bone
7. Soft Tissue Mass
Primary malignant bone neoplasm
Metastasis
Infection
8. Position in Transverse Plane
Central
- enchondroma, simple bone cyst
Eccentric
- GCT, OS, chondrosarcoma, fibrosarcoma, chondromyxoid fibroma, ABC
Cortical
- Nonossifying fibromas, osteoid osteomas, intracortical OS
Juxtacortical
- osteochondromas, parosteal OS
Position in Longitudinal Plane
Epiphyseal
Child
- chondroblastoma until proven otherwise
- consider OM, EG
Adult
- GCT
- arises in metaphysis but quickly penetrates closed physis into epiphysis
- consider clear cell chondrosarcoma, ganglion, eosinophilic granuloma, chondromyxoid sarcoma
- child - chondroblastoma
Metaphyseal
- NOF
- UBC
- osteochondroma
- brodie's abscess
- OS
- CS
Diaphysis
- Ewings
- UBC
- ABC
- enchondroma
- OB
- fibrous dysplasia
Age of malignant osseous lesions
< 1
- metastatic neuroblastoma
1 - 30
- OS
- Ewing's
30 - 60
- CS
- 1° lymphoma
- MFH
> 50
- metastatic disease
- multiple myeloma
Polyostotic versus Monostotic
Non-aggressive polyostotic lesions
- Fibrous dysplasia
- Paget's disease
- Histiocytosis
- Multiple exostosis
- Multiple enchondromatosis
Aggressive polyostotic lesions
- metastases
- Multiple myeloma
- Primary bone tumor with osseous metastases
- An aggressive phase of Paget's disease
- Multifocal osteomyelitis
- Aggressive histiocytosis
- Multifocal vascular bone tumors
Metastasis
Solitary
- rare
- thyroid
- kidney
Appearance
- moth eaten
- wide zone of transition
- no sclerotic rim
Purely lytic
- lung
- breast
- kidney
- thyroid
- GI
- neuroblastoma
Blastic
- prostate
- breast
- bladder
- lung
Mixed
- breast
- prostate
- lung