Bone or cartilage mass imaging

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2]

Overview

Conventional radiography is the method of choice for the diagnosis of primary bone tumors. The evaluation of bone and cartilage tumors will depend on 7 characteristics: periosteal reaction, opacity and mineralization, location, size, margins, cortical involvement, and soft-tissue component.

Imaging

Plain Radiograph

Conventional radiography is the method of choice for the diagnosis of primary bone tumors. The evaluation of bone and cartilage tumors will depend on 7 characteristics: periosteal reaction, opacity and mineralization, location, size, margins, cortical involvement, and soft-tissue component.

Plain Radiograph

What type of bone is involved? ❑ Long bone ❑ Flat bone Where is the lesion located? ❑ Epiphysis ❑ Diaphysis ❑ Metaphysis ❑ Apophysis

Imaging Evaluation

What is the pattern involved? ❑ Osteoblastic ❑ Osteolytic ❑ Mixed What is the transversal location? ❑ Medullary ❑ Cortical ❑ Yuxtacortical What type of margin is involved? ❑ Well defined ❑ Ill-defined ❑ Sclerotic Is there a periosteal reaction? ❑ Yes ❑ No What is the size?

Malignant

Benign

Periosteal reaction

• Periosteal reaction is a non-specific radiographic feature, that occurs with periosteal irritation
• Periosteal reactions may be broadly characterized by pattern and tumor natur (benign/aggressive)
• Useful to characterize a bone lesion
• Common periosteal reactions, include:

• Single layer
• Multilayered (onion-skin)
• Solid
• Spiculated
• Perpendicular (hair-on-end)
• Divergent (sunburst)
• Sloping (velvet)
• Disorganised/complex
• Codman triangle

Location

• Bone and cartilage tumors can be located in different parts of the skeleton, such as:

1.-Axial skeleton

• Skull
• Rib cage
• Hyoid bone
• Vertebral column

2.-Appendicular skeleton

• Long bones

• Location in relation to the physis, includes:

• Metaphysis
• Diaphysis
• Epiphysis
• Apophysis

3.-Flat bones

• Pelvis bone
• Lacrimal bone
• Nasal bone

• Bone and cartilage tumors can also be identified by the transverse location into different categories, such as:

• Medullary
• Cortical
• Juxtacortical

Margin

• The margin evaluation of bone and cartilage tumors, is divided into 3 categories:

• Transition zone

• Narrow
• Wide

• Margin characteristics

• Well-defined
• Ill-defined
• Sclerotic

• Patterns of bone destruction (appearance)

• Moth-eaten

• Examples) Myeloma, metastases, Ewing's sarcoma

• Geographic

• Examples) Non-ossifying fibroma, chondromyxoid fibroma, eosinophilic granuloma

• Permeated

• Examples) Round cell lesions

Opacity and mineralization

• Bone and cartilage tumors opacity depends on the stimulation of osteoclasts or osteoblasts in the bone
• Bone and cartilage tumors can be characterized by the tumor opacity into 3 different categories, including:

• Lytic lesions
• Sclerotic lesions
• Mixed lesions

• Bone and cartilage tumors can be characterized by 2 patterns of mineralization:

• Osseous

• Fluffy
• Cloud-like

• Chondral

• Punctate
• Flocculent
• Arclike

Size

• In some cases, bone tumor size may be helpful to establish the diagnosis.

• Example) Osteoblastoma (>1.5cm) vs osteoid osteoma (<1.5cm)

• Size can range from 0.1 cm - 10cm
• In general, large size tumors are more likely to be malignant, whereas small size tumors tend to be related with benign origin.

Cortical involvement

• In some cases, bone and cartilage tumors lesions can specifically arise within the cortex, in such cases the evaluation will depend on:

• Type of erosion

• Endosteal scalloping
• "Soap bubble” lesions

Soft-tissue component

• Involvement of the soft-tissue is suggestive of a malignant process.

CT

• The majority of bone and cartilage tumors require further evaluation with CT scan.
• CT scan features for the evaluation bone tumors, include:

• Useful for evaluating subtle mineralization in lytic lesions
• Demonstrate occult bone destruction

MRI

• MRI is the standard diagnostic technique of choice for malignant tumors.
• MRI features for the diagnosis of bone and cartilage tumors, include:

• Evaluation of the local extent of a malignant process
• Useful for tumor staging
• Intramedullary and soft tissue extension
• Extension within the bone marrow compartment
• Soft-tissue edema

Gallery

Plain Radiograph

• 
  Osteosarcoma with Codman triangles: the tumor is essentially lytic and destructive with irregular, permeative margins, and soft tissue extension. Codman triangles (reactive periosteal new bone formation around the edges) are very prominent
  Adapted from Creative Commons 3.0
• 
  Giant cell tumor: located on distal radius
  Adapted from Radiopedia
• 
  Pathological fracture: located in the metaphyseal region
  Adapted from Radiopedia
• 
  Rind sign: a lesion surrounded by a layer of thick, sclerotic reactive bone (rind) and is suggestive of fibrous dysplasia
  Adapted from Radiopedia
• 
  Sunburst appearance: a type of periosteal reaction giving the appearance of a sunburst secondary to an aggressive periostitis. Present in aggresive tumors, such as: osteosarcoma, Ewing sarcoma, and osteoblastic metastases (e.g. prostate, lung or breast cancer)
  Adapted from Radiopedia
• 
  Onion skin sign : Also known as "multilayered periosteal reaction" demonstrates multiple concentric parallel layers of new bone adjacent to the cortex, reminiscent of the layers on an onion. Associated with osteosarcoma,Ewing sarcoma, and acute osteomyelitis (*) Parallel layers of new bone
  Adapted from Radiopedia
• 
  Cockade sign: Classic appearance of an intraosseous lipoma of the calcaneus which presents as a well-defined lytic lesion with a central calcification resembling a cockade
  Adapted from Radiopedia
• 
  Geographic skull sign: radiographic appearance which is seen at eosinophilic granuloma. Destructive lytic bone lesion, edges of which may be bevelled, scalloped or confluent
  Adapted from Radiopedia

CT

• 
  String sign : appearance a radiolucent cleavage plane between portions of the tumor and cortex of the affected bone
  Adapted from Radiopedia
• 
  Osteoblastoma: Internal matrix mineralisation is better appreciated on CT
  Adapted from Radiopedia

MRI

• 
  MRI- Onion skin sign
  Adapted from Radiopedia
• 
  MRI-Enchondroma : Well circumscribed somewhat lobulated masses replacing marrow
  Adapted from Radiopedia

References

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