Bone disease

Question 1

Osteosarcoma

Answer 1

Malignant mesenchymal cells 
Knee
ALP positive 
Codman's triangle 
Sunburst appearance

Question 2

Chondrosarcoma

Answer 2

Malignant cartilage cells

Fluffy calcification

Question 3

Ewing’s sarcoma

Answer 3

Sheets of small round cells
CD99+
t(11.22)
Onion skinning of the periosteum

Question 4

Giant cell

Answer 4

Osteoclast-type multinucleate giant cells

Lytic/lucent bone lesions

Question 5

Osteoid osteoma

Answer 5

Bone pain at night relieved by aspirin

Radiolucent nidus

Question 6

Osteoma

Answer 6

Bony outgrowths attached to normal bone

Gardner syndrome: GI polyps + mutliple osteomas + epidermal cysts

Question 7

Enchondroma

Answer 7

Benign tumours of cartilage
Cotton wool calcification
Ollier’s
Maffuci’s = enchondromas + haemangiomas

Question 8

Osteochondroma

Answer 8

Cartilage capped bony outgrowth
Diaphyseal aclasis/hereditary multiple exostoses =
multiple exostoses + short stature + bone deformities

Question 9

Fibrous dysplasia

Answer 9

Bit of bone replaced by fibrous tissue
Albright syndrome = polyostotic dysplasia + cafe au lait spots + precocious puberty 
Chinese letters 
Soap bubble osteolysis 
Shepard's crook deformity

Question 10

Simple bone cyst

Answer 10

Lytic, well defined

Question 11

Osteoblastoma

Answer 11

Speckled mineralisation