Path 11 Bone Pathology

Question 1

Osteoid main component

Answer 1

Type 1 collagen

Question 2

Osteocalcin

Answer 2

Vit K dependent

-Binds to hydroxyapatite -> mineralization

Question 3

Osteonectin

Answer 3

Calcium binding protein

Question 4

Hydroxyapatite crystals

Answer 4

CaPO4 packed around collagen

Question 5

Achondroplasia

Answer 5

FGF-R3 gene mutation (chondrocyte proliferation)

-Sporadic or autosomal dominant

Question 6

Osteogenesis Imperfecta

Answer 6

Improper Type 1 collage synthesis

• Autosomal dominant
• Recurrent fractures
• Blue sclera
• Hearing/Dental abnormalities

Question 7

Osteopetrosis

Answer 7

Carbonic anhydrase II mutation (Howship lacunae)

• No remodelling, bones fill up
• Recessive/Malignant, Dominant/Benign

Question 8

Osteopetrosis clinical

Answer 8

Extramedullary hematopoiesis (Hepatosplenomegaly)

• Erlenmeyer flask deformities
• Neural foramina compression
• Renal tubular acidosis (CA II mutation -> decreased HCO3 resorption)

Question 9

Rickets

Answer 9

Childhood Vit D deficiency

-Pigeon chest, bowing long bones, frontal bossing, rachitic rosary (rib cartilage)

Question 10

Osteomalacia

Answer 10

Adult vit D deficiency

• Weak bones
• Increased osteoid on histo
• Down Ca, PO4
• Up Alk Phosph, PTH

Question 11

Osteoporosis

Answer 11

Reduced bone mass, degenerating matrix

• Vertebral and Hip fractures
• Avoid glucocorticoids

Question 12

Osteoporosis Dx

Answer 12

DEXA scan

-labs are normal

Question 13

Paget disease

Answer 13

Osteoclast dysfunction in elderly

• Osteoclasts hyperresponsive to RANK
• Paramyxovirus etiology

Question 14

Paget disease phases

Answer 14

1- Osteolytic phase (osteoclasts)
2- Mixed phase (osteoblast overdrive)
3- Osteosclerotic phase (both stop)

Question 15

Paget disease histo

Answer 15

Mosaic pattern of lamellar and woven bone

Question 16

Paget disease clinical

Answer 16

Hat gets tighter
Lion facies
Hearing loss
Bone deformity/fracture

Question 17

Avascular osteonecrosis

Answer 17

Children and adolescents

• Carpal bones and head of femur
• Osteoarthritis if subchondral bone involved

Question 18

Osteomyelitis causes (1)

• Most common
• Sexually active
• Diabetics

Answer 18

• Staph Aureus
• Gonorrhea
• Pseudomonas

Question 19

Osteomyelitis causes (2)

• Children
• Sickle cell
• Dog bites
• Direct spread

Answer 19

• H. influenzae
• Salmonella
• Pasteurella
• Mixed bacterial

Question 20

Sequestrum

Answer 20

• Acute

- Bone necrosis due to suppurative/ischemic injury

Question 21

Involucrum

Answer 21

• Chronic

- Reactive bone deposition around infected bone