Neoplasm Radiology

Question 1

List the density, matrix and bone destruction characteristics

Answer 1

Density:
- Lytic/lucent: area of low density so appears dark
- Sclerotic: area of high density so appears white
- Mixed: area of low and high density
Matrix:
- Osteoid: dense amorphous (uniform) sclerotic lesion with white spicules outside bone
- Chondroid: morphic (non-uniform) mixed lesion with grape clusters, little round white balls, arcs and rings
- Fibrous: ground glass
- Indeterminate: lytic lesion
Bone Destruction: only in lytic lesion
- Geographic: localized, concentrated lytic lesion with sharply defined borders with possible sclerotic margin
- Moth eaten: bone destruction with multiple sites and ragged borders
- Permeative: bone destruction at multiple sites with ill defined borders

Question 2

What are the four signs that help to differentiate an aggressive vs non-aggressive bone lesion?

Answer 2

Cortical destruction:
- Less aggressive: no cortical destruction with white cortical border outlining lesion
- Aggressive: cortical destruction with no white border
Periosteal reaction:
- Less aggressive: thick and wavy reaction
- Aggressive: laminated (onion skin) or sunburst reaction
Axis:
- Less aggressive: long axis along length of bone
- Aggressive: short axis along width of bone
Margins: border between lesion and normal bone
- Less aggressive: narrow zone of transition with clearly defined sclerotic margin
- Aggressive: wide zone of transition with ill defined margin

Question 3

Discuss the findings of a non-ossifying fibroma

Answer 3

Most common bone lesion in children
Benign bone lesion
X-ray: sclerotic lesion along metaphysis with narrow transition zone

Question 4

Discuss the radiographic findings of an osteoid osteoma

Answer 4

Benign bone lesion

Radiographic: thick and wavy periosteal reaction, nidus (lytic black oval)

Question 5

Discuss the radiographic findings of a lipoma

Answer 5

Benign bone lesion usually found in the calcaneous in 40-60 year olds
X-ray: lytic lesion with calcified centre and well defined sclerotic margin

Question 6

Discuss the radiographic findings of a osteosarcoma

Answer 6

Malignant bone lesion found in 8-20 year olds. Mostly found in knee and shoulder
X-ray: aggressive osteoid matrix and sunburst periosteal reaction

Question 7

Discuss the radiographic findings of multiple myeloma

Answer 7

Most common malignant bone lesion in adults
Found in vertebrae, pelvis, skull, shoulder, long bones
X-ray: numerous well circumscribed moth eaten lytic lesions, general osteopenia

Question 8

Discuss the radiographic findings of a bone metastasis

Answer 8

Primary: lung, breast, renal cell, prostate
Location: vertebrae, pelvis, proximal femur, humerus, skull
X-ray: lytic > sclerotic > mixed lesion

Question 9

Discuss the principles for open incisional biopsy

Answer 9

Incision: longitudinal incision
Approach: do not expose neurovascular structures, maintain meticulous hemostasis
Biopsy: perform through defined compartment of tumour
Closure: drain brought out in line with surgical incision

Question 10

Discuss the presentation and management of a unicameral bone cyst (UBC)

Answer 10

Epidemiology: Occur in <20, non-neoplastic, usually reduce in size with age
Location: proximal humerus, proximal femur, distal tibia, ilium, calcaneus
Classification: active if adjacent to physis, latent if not
Presentation: asymptomatic, pathological fracture
X-ray: central, lytic, well demarcated metaphyseal lesion, Cyst expansion with thinning of cortices, fallen leaf sign (fallen cortical fragment in pathological fracture)
MRI: bright on T2
Differential: ABC, telangiectatic osteosarcoma
Treatment: non-operative, aspiration and methylprednisolone acetate injection (active lesions), curreatage and bone grafting (latent lesions that are symptomatic or have stress concern)

Question 11

Discuss the presentation and management of osteochondroma

Answer 11

Epidemiology: most common benign bone tumour, adolescents and young adults most common, genetic factors (EXT gene mutation leading to multiple hereditary exostosis - greater risk of chondrosarcoma)
Location: surface of bone near tendon insertion, proximal tibia, distal femur, proximal femur, proximal humerus
Presentation: asymptomatic, painless mass that may have mechanical difficulties or neurovascular compression, grow until skeletal maturity
X-ray: sessile or pedunculated lesion found on surface of bone. Continuous with cortex of native bone. Sessile greater risk of malignant transformation.
Treatment: surveillance, surgery (usually postponed until skeletal maturity)

Question 12

What are some of the risk factors for osteochondroma transformation to chondrosarcoma?

Answer 12

Cartilaginous cap >10-15mm
Bone erosion
Soft tissue calcification
Greater number of exostosis