Other MSK

Question 1

What are the features of osteosarcoma?

Answer 1

Associated with lifting of periosteum off bone producing Codman triangle
+ sunburst appearance on X ray

Question 2

What is the cause of pseudogout + what is seen in the synovial fluid?

Answer 2

Due to deposition of calcium pyrophosphate dihydrate (CPPD)

Synovial fluid shows rhomboid crystals with weak birefringence under polarised light

Question 3

Describe the features of achondroplasia

Answer 3

Mutation in fibroblast growth factor receptor 3 (FGFR3) leads to impaired cartilage proliferation

Question 4

What are the key lab findings in osteomalacia + why?

Answer 4

Low calcium - due to low Vit D
Low phosphate
High PTH - to compensate for low Ca
High alkaline phosphatase - due to osteoblast hyperactivity

Question 5

What is osteopetrosis?

Answer 5

Marble bone disease

Due to poor osteoclast function due to carbonic anhydrase II mutation

Question 6

What is osteogenesis imperfecta?

Answer 6

Brittle bone disease

Congenital defect of bone formation - defect in synthesis of collagen

Question 7

What is Paget’s disease of the bone?

Answer 7

Paramyxovirus infection of osteoclasts
Imbalance between osteoblasts + osteoclasts
Causes mosaic pattern of lamellar bone