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Pathology Yr1 > Malignant bone-cartilage tumours > Flashcards

Malignant bone-cartilage tumours Flashcards

1
Q

What normal cell type does osteosarcoma originate from?

A

Malignant osteoblasts

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2
Q

What is the most common primary malignant bone tumour, excluding haematopoetic tumours?

A

Osteosarcoma

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3
Q

In which bone region does an osteosarcoma commonly occur?

A

Metaphyseal region

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4
Q

At what stage of life does osteosarcoma commonly present?

A

Adolescence

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5
Q

At what age is first incidence of osteosarcoma most common, and in which bone region and why?

A

Under age 20 (puberty growth spurt)

Growth plates of bones have fastest growth due to increased proliferation: allows predisposition to osteosarcoma development

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6
Q

Does the 2nd highest peak incidence of osteosarcoma commonly develop as primary or secondary tumours?

A

Secondary

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7
Q

At which life stage is secondary osteosarcoma most prevalent, and why?

A

Older age (more men)

Have conditions that cause predisposition to osteosarcoma development

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8
Q

Give 3 examples of pre-existing conditions that cause predisposition to secondary osteosarcomas?

A

Paget’s disease

Previous radiation

Bone infarcts

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9
Q

What is the correlation between retinoblastoma and osteosarcoma?

A

Patients with germline/somatic/random mutation of retinoblastoma gene have 1000x risk of developing sporadic (no cause) osteosarcoma

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10
Q

What mutation is caused by Li-Fraumeni syndrome, and how does it affect incidence of osteosarcomas?

A

Germline TP53 gene mutations leading to elevated incidence of osteosarcoma

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11
Q

What is the correlation between tumour suppressor genes and osteosarcoma incidence?

A

70% osteosarcomas occur due to acquired genetic abnormalities in tumour suppressor genes

eg.RB, p53, CDKN2A (gene encodes two tumour suppressors, p16 (a negative regulator of cyclin-dependent kinases) and p14 (which augments p53 function)

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12
Q

Which 2 oncogenic cell-cycle regulators are overexpressed by low-grade osteosarcomas, and what are their oncogenic functions?

A

MDM2 (inhibits p53)

CDK4 (inhibits RB)

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13
Q

Describe the macroscopic appearance of osteosarcomas?

A

Grey/white, bulky mass with cut surface that shows haemorrhaging, fibrosis, cystic degeneration

Can see Codman triangle

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14
Q

Describe the radiological appearance of the centre of the osteosarcoma mass itself?

A

Mixed radiolucent/lytic areas and sclerotic areas

Infiltrative/not well-defined border

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15
Q

Describe what is meant by the radiological sunburst/’hair on end’ periosteal reaction, in osteosarcomas?

A

Lesion grows so fast that periosteum has insufficient time to lay down another bone layer, instead sharpey’s fibres stretch perpendicular to bone surface

Occurs in other aggressive bone lesions too

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16
Q

Describe what is meant by the radiological Codman triangle, in osteosarcomas?

A

Tumour breaks through cortex into periosteum that has insufficient time to completely ossify, so only raised periosteum edge ossifies, forms a triangle shape

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17
Q

Give examples of aggressive bone lesions that commonly have the radiological sunburst sign?

A

osteosarcoma

Ewing sarcoma

osteoblastic metastases from prostate, lung, breast cancer

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18
Q

Give examples of aggressive bone lesions that commonly have the radiological Codman triangle sign?

A

osteosarcoma

Ewing sarcoma

metastases

chondrosarcoma

osteomyelitis setting

giant cell tumour

aneurysmal bone cyst

19
Q

Describe the 2 characteristic microscopic features of osteosarcoma?

A

Unmineralised (light pink) and mineralised (dark pink) trabeculae in interconnected network

Between trabeculae, malignant osteoblasts secrete osteoid (dark purple)

20
Q

What normal cell type does chondrosarcoma arise from?

A

Chondrocytes (cells that produce cartilage)

21
Q

What substance does a chondrosarcoma produce?

A

Cartilage

22
Q

Which bones do chondrosarcomas commonly develop in, and give 3 specific bony structures?

A

Axial skeleton and proximal extremities

Eg. pelvis, ribs, shoulders

23
Q

Which age range is commonly affected by chondrosarcomas?

A

Older adults (over 40 yrs old)

24
Q

Are chondrosarcomas equally common in men and women?

A

Twice as common in men

25
Q

Are chondrosarcomas mostly primary or secondary?

A

Primary

15% are secondary

26
Q

Which 2 types of tumours do secondary chondrosarcomas usually arise from?

A

Enchondroma

Osteochondroma

27
Q

What 2 forms of chondrosarcomas are more aggressive then its conventional form?

A

Mesenchymal

Dedifferentiated (transient process by which cells become less specialized and return to an earlier cell state within the same lineage)

28
Q

What is the main macroscopic feature of chondrosarcomas?

A

Painful enlarging mass

29
Q

What are the main 3 radiological features of chondrosarcomas?

A

Ring and arc patterns/clumped densities

Soft tissue mass

Destroyed bone cortex

30
Q

What are the 3 main microscopic findings of chondrosarcomas?

A

Nuclear pleomorphism

Higher nuclear to cytoplasmic ratio

Irregular cells membranes

31
Q

Do grade 1 chondrosarcomas usually metastasise?

A

No

32
Q

How do grade 3 chondrosarcomas usually metastasise, and to where?

A

Haematogenous spread

Lungs

33
Q

Which normal cell type does Ewing sarcoma arise from, and where in the bone?

A

Neuroectodermal cells

Medullary cavity

Malignant cancer

34
Q

What are the 1st and 2nd most common childhood primary bone tumours?

A

Osteosarcoma

Ewing sarcoma

35
Q

Is Ewing sarcoma more common in boys or girls, and what is the typical age range?

A

Boys

15 years old and younger

36
Q

Does Ewing sarcoma normally metastasise?

A

Yes

37
Q

Does Ewing sarcoma usually respond well to chemotherapy?

A

Yes

38
Q

What chromosomal mutation is typically associated with Ewing sarcoma?

A

Balanced 11;22 translocation: Fuses the EWSR-1 gene on chromosome 22

to the FLI-1 gene on chromosome 11

39
Q

What is the 2 characteristic microscopic findings of Ewing sarcoma, and what normal cells can these be mistaken for?

A

Small, round, blue cells with little cytoplasm

Psuedo-rosettes: Cells cluster around pink necrotic area

Which resemble lymphocytes

40
Q

What are the 4 main radiological findings of Ewing sarcoma?

A

Permeative ‘moth-eaten’ radiolucent areas of bone
diaphysis

Large soft-tissue mass with no osteoid

Lamellated/onion skin periosteal reaction: Bony concentric cells

Sunburst/’hair on end’ periosteal reaction

41
Q

Why does the onion skin periosteal reaction occur in bone?

A

Lesion grows unevenly in fits so periosteum has time to lay down a bone layer until lesion grows again, causing pattern of concentric bony shells

42
Q

What is Wilms tumour/nephroblastoma?

A

Rare, malignant kidney cancer that affects children

43
Q

What is rhabdomyosarcoma, and what 6 body areas does it commonly affect in children?

A

Most common soft tissue sarcoma in children, that develops from muscle or fibrous tissue

commonly affects head, neck, bladder, testes, womb, or vagina

Pathology Yr1 (20 decks)

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