Histopathology - Metabolic Bone Diseases

Question 1

What are some metabolic bone diseases?

Answer 1

• Osteoporosis
• Osteomalacia/rickets
• Primary Hyperparathyroidism
• Paget’s disease
• Renal Osteodystrophy

Question 2

What is the aetiology and some RFs of osteoporosis?

Answer 2

Aetiology:
- Age-related (post-menopausal females)
- Secondary to systemic disease/drugs

RFs:
- Increasing age
- Female
- Smoking
- Poor diet
- Low BMI

Question 3

What are the disease features + symptoms of osteoporosis?

Answer 3

Features:
- Decreased Bone mass
- DEXA Scan T-score <-2.5

Sx:
- Low impact fractures (Hip, NOF, Vertebrae, wrist)
- Pain (back)

Question 4

What are some histological + biochemical findings of Osteoporosis?

Answer 4

Histo:
- Loss of cancellous bone

Bio:
- Normal Ca
- Normal PO4
- Normal ALP

Question 5

What is the aetiology and some RFs for Osteomalacia/rickets?

Answer 5

Aetiology:
- Low dietary Vit D
- Low Sunlight
- Malabsorption of Vit D (GI causes)
- Genetic causes

RFs:
- Poor diet
- Malabsorption
- CLD
- CKD
- Lack of sunlight

Question 6

What are the disease features + Sx of Osteomalacia + rickets?

Answer 6

Features:
- Low bone mineralisation

Adult Sx:
- Bone pain/tenderness
- Proximal muscle weakness

Child Sx:
- Bone pain
- Bowing tibia
- Rachitic rosary
- Frontal bossing
- Pigeon chest
- Delayed walking

Question 7

What are the XR findings for osteomalacia/rickets?

Answer 7

Looser’s Zones
- Pseudofractures

Splaying of metaphysis

Bowing of legs in rickets

Question 8

What are the histological + biochemical findings in osteomalacia/rickets?

Answer 8

Histo:
- Excess unmineralised bone (osteoid)

Bio:
- Normal/low Ca
- Low PO4
- High ALP

Question 9

What is the aetiology and some RFs for Primary Hyperparathyroidism?

Answer 9

Aetiology:
- Excess PTH production leads to increased Ca reabsorption + PO4 excretion

• Parathyroid adenoma
• Hyperplasia
• Carcinoma
• MEN

RFs:
- Secondary HyperPTH leads to DRF
- Low Vt D
- Malabsorption

Question 10

What are the disease features + some symptoms of Primary Hyperparathyroidism?

Answer 10

Features:
- Bone changes of osteitis
- Fibrosa cystica

Sx:
- Hypercalcaemia (Moans, stones, bone, groans, thrones)

Question 11

What are some XR findings for Primary Hyperparathyroidism?

Answer 11

• Brown’s tumour (collection of multinucleate giant cells)
• Salt + pepper skull
• Subperiosteal bone resorption in phalanges

Question 12

What are the histological + biochemical findings for Primary hyperparathyroidism?

Answer 12

Histo:
- Osteitis Fibrosa Cystica (marrow fibrosis + cysts = Brown Tumour)

Bio:
- High Ca
- Low/normal PO4
- High PTH (or inappropriately normal)

Question 13

What is the aetiology + some RFs for Paget’s disease?

Answer 13

Aetiology:
- A disorder of bone turnover

RFs:
- >50yrs old
- M=F
- Caucasian

Question 14

What are the disease features and some Sx of Paget’s disease?

Answer 14

Features:
- Both lytic + sclerotic lesions
- 3 stages (Osteolytic, Mixed, Osteosclerotic)

Sx:
- Bone pain
- Microfractures
- Nerve compression (leads to sensorineural deafness/sciatica)
- Skull changes
- Increased head size
- Deafness
- High output cardiac failure

Question 15

What are the XR findings for Paget’s disease?

Answer 15

• Mixed lytic + sclerotic
• Skull: Osteoporisis, Circumscripta, cotton wool
• Vertebrae: Picture frame, Ivory vertebrae
• Pelvis: Sclerosis + lucency

Question 16

What are the histological + biochemical features of Paget’s disease?

Answer 16

Histo:
- Huge osteoclasts (with >100 nuclei)
- Mosaic pattern of lamellar bone (like jigsaw puzzle)

Bio:
- Normal Ca
- Normal PO4
- Really High ALP

Question 17

What is the aetiology of Renal Osteodystrophy?

Answer 17

• Osteitis fibrosa cystica (secondary hyperparathyroidism)
• Osteomalacia
• Osteosclerosis
• Adynamic bone disease
• Osteoporosis

All skeletal changes associated with CKD

Question 18

What are the disease features, Sx and histological features of Renal Osteodystrophy?

Answer 18

Dependent on form of bone disease