2s: Bone Tumours

Question 1

Bone tumour epidemiology

Answer 1

o Malignant tumours are 60 x less common than lung cancer
o Primary malignant bone tumours are more common in children and young adults
o Site predilection – around the knee is most common

Question 2

Clinical presentation and hx of bone tumours

Answer 2

Question 3

Role of X-ray in diagnosing bone tumours

Answer 3

Evaluate site, size and margin of lesion

Solitary or multiple lesions

Extension into the soft tissue

Associated disease or fracture

Question 4

What to do if primary bone tumour suspected

Answer 4

REFER patient urgently to a specialist centre

Question 5

Ix for bone tumours

Answer 5

Diagnosis is through an XR and a biopsy

• US-guided Jamshidi needle biopsy
• Open biopsy for inaccessible lesions
• Imprint (cytology) preparations useful

Question 6

Give examples of TUMOUR-LIKE CONDITIONS

Answer 6

Fibrous Dysplasia

Metaphyseal fibrous cortical defect/non-ossifying fibroma

Reparative giant cell granuloma

Ossifying fibroma

Simple bone cyst

Question 7

Fibrous Dysplasia: epidemiology, features, site, XR appearance

Answer 7

More common in females; age <30yo

Mono-ostotic is more common than poly-ostotic

Site: any bone (ribs and proximal femur are most common)

X-ray appearance: ‘soap bubble’ osteolysis

<1% will undergo malignant transformation

• Caused by a mutation in a G-protein (GNAS mutation chr20; q13)
• If multiple bones affected it is likely to be benign (unless it is metastatic cancer)

Histologically = marrow replaced by fibrous stroma with rounded trabecular bone (used to be called Chinese letters)

Fibrous Dysplasia in femoral head (Shepherd’s Crook) = micro fractures lead to a change in shape

Question 8

What are the two types of benign bone tumours, and examples of each

Answer 8

Cartilaginous***

• osteochondroma
• enchondroma
• chondroblastoma

Bone forming

• osteoid osteoma
• osteoblastoma
• osteoma

Question 9

Osteochrondroma features

Answer 9

End of long bones

male, 10 - 20 y/o

mimic normal tubular bones = cartilaginous surface overlying normal trabecular bone

Question 10

Echondroma features

Answer 10

Cartilaginous proliferation WITHIN bone

hands and feet

XR → popcorn calcification

Histology = well-circumscribed cartilage proliferation, well demarcated, may erode through cortex of bone but does NOT come through cartilaginous surface

Question 11

Give an example of a borderline malignancy condition and it’s features

Answer 11

Giant Cell Tumour (female version of osteochondroma)

End of long bones, 20-40 y/o

XR = lytic appearance

Histology = osteoclast giant cells (NOT neoplastic, the tumour cells are the stromal cells) on background of spindle/ovoid cells

Locally aggressive, may recur, and can metastasise

Question 12

Osteoblast vs osteoclast

Answer 12

osteoblast build bone

osteoclast break bone

Question 13

Cancers that spread to the bone

Answer 13

Question 13

Cancers that spread to the bone

Answer 13

Question 14

What are the 3 types of malignant bone tumour?

Answer 14

Osteosarcoma → forms bone

Chondrosarcoma → forms cartilage

Ewing’s sarcoma/PNET → undifferentiated mesenchymal tumour

• Primitive peripheral neuroectodermal tumour

Question 15

Osteosarcoma

Answer 15

10 - 30 y/o, MALES

end of long bones (older pts in jaw)

XR findings = elevated periosteum (Codman’s triangle), metaphyseal, lytic, permeative

Histology = malignant mesenchymal cells +/- bone and cartilage formation

Prognosis = POOR

Classification:

• site within bone (e.g. intramedullary, intracortical, surface)
• degree of differentiation (high, intermediate, low)
• multicentricity (synchronous/metasynchronous)
• primary or secondary

Question 16

Chondrosarcoma

Answer 16

Malignant cartilage producing tumour

>40 y/o

axial skeleton, pelvis, proximal femur, proximal tibia

XR = lytic with fluffy calcification

Histology = malignant chondrocytes w/ or w/o chondorid matrix, may differentiate to high grade chondrosarcoma

Classification:

• site: intramedullary, juxtacortical
• histology = conventional (myxoid [composed of clear, mucoid substance] or hyaline), clear cell (low grade), dedifferentiated (high grade), mesenchymal

Question 17

Ewing’s Sarcoma (PNET): Primitive peripheral neuroectodermal tumour

Answer 17

Highly malignant small round cell tumour

<25 y/o, 15 y/o median

diaphysis/metaphysis of long bones, pelvis

XR:

• onion skinning of periosteum
• lytic with or without sclerosis

Hx = sheets of small round cells

translocation 11:22 (EWSR1/FLI1) (q24; q12)

Question 18

Soft tissue tumours definition and site

Answer 18

mesenchymal proliferations which occur in the extra-skeletal, non-epithelial tissues of the body – excluding the meninges and lymphoreticular system

Site: anywhere

• Majority in the large muscles of the extremities
• Chest wall, mediastinum, retroperitoneum

Age: mostly >55 years; NO proven racial variation

Aetiology is uncertain, but factors that contribute include:

• Genetic Chemical carcinogens Physical (asbestos, foreign body)
• Viruses Immunodeficiency

Question 19

give 3 types of soft tissue tumours

Answer 19

Liposarcoma

Spindle cell sarcoma

Pleomorphic sarcoma

Question 20

Diagnostic techniques for soft tissue tumours

Answer 20

• Immunohistochemistry EM
• Cytogenetics FISH
• M-FISH SKY
• CGH PCR
• RT-PCR

Question 21

Chromosomal translocation

Answer 21

Question 22

Bone tumours prognostic factors

Answer 22

Question 23

Bone tumour staging

Answer 23

Question 24

Why give HRT until age of 51 in POI?

Answer 24

The mainstay of treatment is hormone replacement therapy (which can also be given as the combined oral contraceptive pill) which is given until the age of natural menopause (around 51 years) to prevent osteoporosis, as well as to protect against symptoms of oestrogen deficiency and possible cardiovascular complications.