Histopathology 8 : Bone pathology

Question 1

2 main types of bone in the body? Where are these bones?

Answer 1

Cortical bone (80% of skeleton) -appendicular skeleton
cancellous bone - axial skeleton + pelvis

Question 2

Main function of cortical bone and cancellous bone, respectively

Answer 2

Cortical: mechanical and protective function (85% calcified)
Cancellous: metabolic function

Question 3

3 main types of bone cells

Answer 3

Osteoblasts
Osteoclasts
Osteocytes

Question 4

Osteoclast cell type?

Answer 4

Macrophage family

Question 5

What are osteocytes?

Answer 5

Osteoblast like cells but they sit in the LACUNAE

Question 6

How do osteoblasts regulate osteoclast function?

Answer 6

Osteoblasts have osteoprotegerin receptors which bind to RANK on osteoclast precursors (osteoprotegrin acts as a RANK ligand) which stops osteoclast precursor differentiation in to an osteoclast

Question 7

Denosumab MOA

Answer 7

Monoclonal antibody which mimics osteoprotegrin (RANK ligand AB)

Question 8

3 main catégories of metabolic bone disease

Answer 8

Non-endocrine: age related osteoporosis
Endocrine (Vit D, PTH etc)
Disuse osteopenia

Question 9

Main cause of osteoporosis

Answer 9

90% due to insufficient calcium intake and post-menopausal oestrogen deficiency

Question 10

Which bone cells do steroids have an effect on?

Answer 10

Osteoclasts
Osteoblasts
Osteocytes

Question 11

Common sites of fracture in osteoporosis

Answer 11

Colles’, NOF, hip

Question 12

T score vs Z score

Answer 12

T score: comparison of person’s bone density with that of a healthy 30 year old
Z-score: comparison to age matched population

Question 13

Where is bone biopsy taken from in suspected bone metabolic disease?

Answer 13

Iliac crest

Question 14

4 organs affected by pTH

Answer 14

Bone
Kidneys
Parathyroid
Small intestine (proximal)

Question 15

What is osteomalacia?

Answer 15

Defective bone mineralisation

Question 16

2 types of osteomalacia?

Answer 16

Deficiency of Vit D

dEFICIENCY of phosphorus

Question 17

Classical radiological findings in osteomalacia

Answer 17

Bowing of legs (rickets)

Horizontal pseudo fractures in looser’s zones

Question 18

Skeletal changes in hyperparathyroidism

Answer 18

Osteitis fibrosa cystica

Question 19

biochemical picture in hyperparathyroidism

Answer 19

hypercalcaemia

hypophosphataemia (increased phosphate excretion in urine)

Question 20

Most common cause of hyperparathyroidism

Answer 20

Parathyroid adenoma

Question 21

Histology in hyperparathyroidism

Answer 21

Brown cell tumours

Question 22

What are brown cell tumours?

Answer 22

multinucleate giant cells

Question 23

What is required for the histological diagnosis of hyperparathyroidism?

Answer 23

Brown cell tumours

Question 24

skeletal changes in renal osteodystrophy? (5)

Answer 24

1. osteomalacia (Due to low calcitriol synthesis)
2. Increased bone resorption –> osteitis fibrous cystic
3. Osteosclerosis
4. Growth retardation
5. Osteoporosis

Question 25

3 stages of Paget's disease

Answer 25

osteolytic osteolytic-osteosclerotic quiescent osteosclerotic

Question 26

Virus possibly involved in the pathophysiology of Paget's

Answer 26

Parvomyxovirus

Question 27

bone changes consistent with osteitis fibrosa cystica

Answer 27

Brown tumours | Salt and pepper skull

Question 28

Osteomyelitis common sites

Answer 28

Vertebrae, jaw secondary to dental abscess, toe secondary to diabetic ulcer, long bones (metaphysis)

Question 29

Investigations for osteomyelitis

Answer 29

Xray, eventually becomes lytic | 2nd line = MRI (more sensitive)

Question 30

Most common bacterial infection in osteomyelitis

Answer 30

S.aureus

Question 31

Sickle cell + osteomyelitis

Answer 31

SCD

Question 32

IVDU + osteomyelitis --> ? bacteria

Answer 32

Pseudomonas

Question 33

TB osteomyelitis histology

Answer 33

Granulomas + langerhans-type giant cells

Question 34

neuropathic joints in syphilis = ?

Answer 34

Tabes dorsaliis

Question 35

what is Lyme disease?

Answer 35

inflammatory arthropathy

Question 36

name of skin rash in lyme disease

Answer 36

erythema chronicum migrans

Question 37

osteoarthritis radiological changes

Answer 37

loss of joint space subchondral sclerosis bone cysts osteophytes

Question 38

main sites affected in osteoarthritis?

Answer 38

Vertebrae Hips Knees

Question 39

Name of two signs in the hands in osteoarthritis

Answer 39

Bouchards (PIP) and Heberden's (DIP) nodes

Question 40

HLA associations in rheumatoid arthritis

Answer 40

HLADR4 HLADR1

Question 41

Class of immunoglobulin of rheumatoid factor

Answer 41

IgM

Question 42

Structure of the immune complexes in rheumatoid arthritis?

Answer 42

The Rf (IgM) forms complexes with IgG and these immune complexes may be responsible for extra-articular diseases

Question 43

RA sites involved, which joint is spared?

Answer 43

Small joints of hands and feet, DIPJ spared

Question 44

characteristic deformities include

Answer 44

swan neck deformity boutonnieres radial deviation of wrist ulnar deviation of fingers Z shaped thumb

Question 45

severe chronic relapsing synovitis

Answer 45

RA

Question 46

Grimley-Sokoloff cells

Answer 46

multinucleate giant cells in RA

Question 47

SITES OF PSEUDOGOUT

Answer 47

Knees (calcium pyrophosphate | Knees +shoulders (calcium phosphate)