Pathology of Bone, Joint and Soft Tissue

Question 1

What are the bone forming tumours?

Answer 1

• Osteoma
• Osteoid osteoma and osteoblastoma
• Osteosarcomas

Question 2

What are the cartilage forming tumours?

Answer 2

• Osteochondroma
• Chondromas
• Chondrosarcoma

Question 3

What are the bone and related tumours?

Answer 3

• Bone forming tumours
• Cartilage forming tumours
• Fibrous and osseous tumours
• Miscellaneous (Ewing sarcoma, giant cell tumour, aneurysmal bone cyst)
• Metastases

Question 4

What is Paget’s disease?

Answer 4

Disorder of bone formation resulting in deformity, decreased structural strength, increased bone mass and subsequent effects on other symptoms

Question 5

What are the 3 phases of Paget’s disease?

Answer 5

• Lytic
• Mixed
• Burnt out

Question 6

Cause of Paget’s disease?

Answer 6

• Hereditery component (SQSTM1 gene in 40-50% familial causes)
• Osteoclast activation
• x7 more common in first degree relatives

Question 7

Epidemiology paget’s disease?

Answer 7

• Middle age - elderly
• M>F
• Rare

Question 8

What is leontiasis osier?

Answer 8

Lion like face (big part of triangle at top of face) occurs as part of Paget’s disease.

Question 9

Clinical features of Paget’s disease?

Answer 9

• Leontiasis ossea
• Long bone bowing
• Radiological cortex thickening
• Chalkstick and vertebral compression fractures
• Secondary osteoarthritis

Question 10

How is Paget’s disease treated?

Answer 10

Calcitonin and bisphosphonates for treatment

Question 11

Macroscopic features of Paget’s disease?

Answer 11

Thickened, deformed vascular bone

Question 12

Microscopic features of Paget’s disease?

Answer 12

Mozaic, haphazard, jigsaw patterns with variable osteoclastic/blastic activity depending on the stage. Increased marrow vascularity

Question 13

Causes of AVN?

Answer 13

All related to ischaemia

• Steroids
• Trauma
• Infection
• Dysbarism (gas emboli)
• Pregnancy (amniotic fluid emboli)
• Collagen disease
• Sickle cell disease
• Tumours
• Pancreatitis (fat emboli)

Question 14

How does AVN often present?

Answer 14

Pain: acutely when subchondral; may result in OA. Depends on site

Question 15

Macroscopic features of AVN?

Answer 15

• Medullary cancellous bone with well demarcated lesion
• Cortex has collaterals
• Cartilage is usually viable
• Fracture can occur

Question 16

Microscopic features of AVN?

Answer 16

• Lacunae devoid of osteocytes
• Necrotic fat cells
• Sometimes sloughing of articular cartilage

Question 17

What is osteomyelitis?

Answer 17

Inflammation of bone related to an isolated focus of infection but may be associated with system sepsis

Question 18

Focus of dead bone fragment in centre of osteomyelitis lesion?

Answer 18

Sequestrum

Question 19

Most common site of septic arthritis?

Answer 19

Knee

Question 20

What is an osteosarcoma?

Answer 20

A malignant mesenchyal tumour in which the tumour cells produce bone

Question 21

What is the cause of osteosarcoma?

Answer 21

• Mutations in RB and p53

- Cell cycle and DNA repair abnormalities seem important

Question 22

Where are osteosarcomas most common?

Answer 22

Sites of bone growth; knee commonest at metaphysis (25%)

Question 23

Age of osteosarcoma onset?

Answer 23

Bimodal incidence:

-75%

Question 24

Radiographic features of osteosarcoma?

Answer 24

-Destructive lytic and blastic infiltrating lesion with reactive raised periosteum (Codman’s triangle)

Question 25

General pattern of sarcoma v carcinoma spread?

Answer 25

Carcinoma by lymphatics

Sarcoma by blood

Question 26

Microscopic features of osteosarcoma?

Answer 26

• Pleomorphic cells (sometimes multinucleated) with abnormal mitoses
• producig bone
• Multi centric or solitary
• Primary or secondary (e.g. Paget)
• Histological e.g. osteoblastic, chondroblastic, fibroblastic

Question 27

What is a sarcoma?

Answer 27

Malignant soft tissue tumour

Question 28

What is a benign/malignant skeletal muscle tumour?

Answer 28

Rhabdomyoma / rhabdomyosarcoma