Histopathology - Bone tumours

Question 1

What is the preferred investigation for diagnosing bone tumours?

Answer 1

US guided Jamshidi needle biopsy

Question 2

What is “shepherd’s crook deformity” a reference to?

Answer 2

Fibrous dysplasia involving the femoral head

Question 3

Recall 7 benign conditions of the bone

Answer 3

Fibrous dysplasia
Osteoma
Osteoid osteoma
Osteoblastoma

Simple Bone cyst
Enchondroma - Cartilaginous
Osteochondroma - Cartilaginous

Question 4

How does osteochondroma mimic bone in appearance?

Answer 4

They have a cartilaginous surface overlying normal cortical + trabecular bone

Question 5

In which bones is osteochondroma most likely to present?

Answer 5

Long bones

Question 6

How will enchondroma appear on XR?

Answer 6

“popcorn” pattern

Question 7

Is a giant cell tumour of bone benign or malignant?

Answer 7

Borderline malignant

Question 8

How do giant cell bone tumours appear under the microscope & XR?

Answer 8

Osteoclasts on a background of ovoid cells

common in females aged 20-40

-XR shows lytic apperance

Question 9

What are the 3 types of malignant bone tumour?

Answer 9

Osteosarcoma (bone-forming)
Chondrosarcoma (cartilage-forming)
Ewing’s sarcoma (undifferentiated mesenchymal)

Question 10

Recall the typical age of presentation for each of the 3 types of malignant bone tumour

Answer 10

Osteosarcoma: adolescence
Chondrosarcoma: >40 years
Ewing’s sarcoma: <20 years

Question 11

Recall the typical site affected for each of the 3 types of malignant bone tumour

Answer 11

Osteosarcoma: knee
Chondrosarcoma: pelvis/ axial & femur/tibia skeleton
Ewing’s sarcoma: long bones + pelvis

Question 12

Recall the typical X ray appearance of each of the 3 types of malignant bone tumour

Answer 12

Osteosarcoma: Codman’s triangle, Sunburst appearance
Chondrosarcoma: fluffy calcification
Ewing’s sarcoma: Onion-skinning of periosteum

Question 13

What is a “Codman’s triangle”?

Answer 13

The triangular area of new subperiosteal bone that is created when a lesion, often a tumour, raises the periosteum away from the bone.

Question 14

Which of the 3 types of malignant bone tumour has the best prognosis?

Answer 14

Chondrosarcoma

Question 15

What gene mutation is associated with Ewing’s sarcoma?

Answer 15

11:22 translocation

Question 16

Which type of malignant bone tumour will stain for CD99 and MICC2?

Answer 16

Ewing’s sarcoma

Question 17

Which patients are most at risk of developing Ewing’s tumour in soft tissue?

Answer 17

Immunocompromised patients

Question 18

where in body is common affected in enchondroma? What age group too

Answer 18

Hands
Middle aged

Question 19

2 XR findings of fibrous dysplasia?

Answer 19

soap bubble osteolysis
shepherds crook deformity (femoral head)

Question 20

bone will appear histologically normal in what 2 benign conditions

Answer 20

osteoid osteoma
osteoma

Question 21

is osteoid osteoma more common in M or F

Answer 21

M (2:1)

Question 22

is fibrous dysplasia more common in M or F

Answer 22

F

(f for fibrous)

Question 23

McCune albright syndrome is related to what benign condition? what’s the triad

Answer 23

McCune albright = polyostotic fibrous dysplasia + cafe au lait spots + precocious puberty

Question 24

mushroom appearance on XR =

Answer 24

Osteochondroma

looks like a bony projection on the external surface of a bone, like a bony mushroom on a stalk, usually near a growth plate area

Question 25

what’s the most common benign tumour of bone. What age

Answer 25

Osteochondroma
Adolescent

Question 26

XR finding of osteoid osteoma

Answer 26

radiolucent nidus w sclerotic rim = bulls eye

Question 27

histological appearance of bone in fibrous dysplasia

Answer 27

woven bone with odd irregular shapes (often described as “chinese characters”)

Question 28

outline 4 differences between benign and malignant bone conditions

Answer 28

benign = no peirosteal reaction, acute reaction in malignant (codmans's, onion ski, sunburst appearance) 
benign = well developed bone formation, malignant = varied bone formation 
benign = intraossesu and even calcification, malignant = extraosseus and irregular calcification