Definition:
Paget's disease (named after British Surgeon Sir James Paget) is chronic, progressive disease of bone characterized by abnormal and excessive remodelling of bone in which there is increased osteoclastic activity followed by accelerated but abnormal bone formation and increased vascularity of bone due to which bone becomes enlarged, weakened, and deformed.
Etiology:
Exact etiology is unknown.
1. Bone remodelling abnormality
2. Genetic: Autosomal dominant
3. Viral: Identification of nuclear inclusion bodies in osteoclast (Paramyxovirus, Measles and canine distemper virus)
4. Inflammatory
5. Autoimmune
6. Vascular disorder
Clinical Features:
- 2nd most commonest osteodystrophy condition after osteopetrosis
- Age: > 50 yrs (rarely below 20 years), M = F
- Sites: Pelvis, femur, spine, skull, tibia and lesser extent in clavicles, scapula, ribs, upper limbs
Signs and symptoms:
- Mostly asymptomatic but bone pain (most common complain)
- Affected bone is thickened, enlarged and weak
- Skull: expansion and frontal bossing and Platybasia
- Vertebrae: L abs S
- When facial bones involved: headache, paresthesia, hearing loss, blindness etc.
Oral manifestations:
Maxilla> Mandible
1. Progressive jaw enlargement
2. Alveolar ridge widening
3. Flattening of palate
4. Excessive spacing between teeth (as teeth migrate due to point2)
5. Tightening of dentures in edentulous patients due to expanding alveolar ridge
6. Mouth may remain open as disease progresses due to jaw enlargement
Radiographic features:
Three phases of Paget's disease are:
1. Osteoclastic/ osteolytic phase: bone resorption initially
- Destructive radiolucent areas (single, multiple or diffuse)
2. Mixed or osteoclastic-osteoblastic phase: Bone resorption along with new bone formation
- patchy mixed radiolucency or radiolucency with radiopacity Cotton-wool appearance
called
3. Osteoblastic phase: more bone formation phase
Other radiographic features:
- bone enlargement with cortical thickening
- Increases trabeculae, deformity, and bowing of bone
- Jaw: loss of lamina dura and generalized hypercementosis of teeth
- Rarely root absorption
Note: paget's disease may stimulate chronic, diffuse, and sclerosing osteomyelitis
Lab Findings:
1. Bone-specific alkaline phosphatase(BSAP) elevated up to 250 Bodansky units (Normal = 30-40) (Ca, P, serum acid phosphatase → Normal)
2. Urinary hydroxyproline level elevated
3. Specific markers of bone resorption are Pyridinium collagen cross links:
- N-terminal telopeptide (NTX) and
- Collagen C-telopeptide (CTX)
i.e. High Alpha CTX- Beta CTX ratio is seen
Histologic Findings:
Initial osteolytic phase:
- Increased bone resorption, increased osteoclasts, seen as multinucleated giant cells
- Mixed phase:
→ Small, irregular, fragments of newly formed woven bone which"Jig saw puzzle" or "mosaic"pattern
appear to be united in a characteristic
→ Haematoxyphilic reversal lines (due to repeated bone resorption and bone formation)
- Later osteoblastic stage:
compact bony islands and marrow filled with vascularised fibrous tissue, alo no usual haversian system
Treatment:
- No specific treatment
- NSAIDS like aspirin to alleviate pain of bone or joint
- Bisphosphonates ; Adhere to the mineralized surface and inhibit the osteoclastic activity
- Calcitonin: A parathormone antagonist inhibit osteoclastic activity
Treatment:
1. Aspirin or acetaminophen
2. Bisphosphonates
3. Calcitonin
Prognosis:
Polyostotic → Poor
Monostotic → Good
Complications:
1. Stress fractures (Sites: Femur, tibia, humerus, spine etc)
2. Secondary sarcomas: Osteosarcoma> Chondrosarcoma> Fibrosarcoma
Some Viva Questions:
Q. What is Platybasia?
- Descent of cranium onto the cervical spine
Q. Radiographic differential diagnosis of paget's disease:
- Cotton wool appearance;
1. Osteosarcoma
2. Fluid cemento-osseous dysplasia
3. Sclerosing osteomyelitis
4. Acute osteopetrosis
Q. Why there is rise in skin temperature of affected bone in Paget's disease?
- Abnormal and excessive remodelling of bone
↓
initially increased osteoclastic activity
↓
followed by accelerated but abnormal bone formation
and increased vascularity of bone combined with cutaneous vasodilatation
↓
cause increase in regional blood flow
↓
rise in skin temperature of affected bone
Q.Why there is "jig saw" or "mosaic" pattern of bone histologically in Paget's disease?
- Due to basophilic reversal lines because of continuous resorption and formation of bone.
Some Important MCQS
1. Paget's disease is a defect of
a. Osteoblastic differentiation and maturation
b. Osteoclastic differentiation and maturation
c. Abnormal and excessive remodelling of bone
d. Fibroblastic differentiation and maturation
Correct answer is c.
2. Correct for Paget's disease
a. Initially bone resorption/ osteoclastic activity
b. Bone resorption followed by formation of woven bone
c. Finally osteoblastic activity
d. All of the above
Correct answer is d.
3. Age of onset of Paget's disease is
a. Below 20 years
b. 20 to 40 years
c. Above 50 years
d. None of the above
Correct answer is c.
4. The most common presenting complaint of Paget's disease is
a. Headache
b. bone pain
c. Swelling
d. Bone fracture
Correct answer is b.
5. Platybasia is the characteristic feature of
a. Paget's disease
b. Osteosarcoma
c. Osteopetrosis
d. Fibrous dysplasia
Correct answer is a.
6. Tightening of dentures because of expanding alveolar ridge is the characteristic feature of
a. Paget's disease
b. Osteosarcoma
c. Osteopetrosis
d. Fibrous dysplasia
Correct answer is a.
7. Which one is not the phase of paget's disease?
a. Osteoclastic phase
b. Mixed phase
c. Double phase
d. Osteoblastic phase
Correct answer is c.
8. Cotton-wool appearance is the characteristic feature of
a. Fibrous dysplasia
b. Osteosarcoma
c. Osteopetrosis
d. Paget's disease
Correct answer is d.
9. Which one is not the specific marker for Paget's disease?
a. Serum alkaline phosphatase
b. Serum acid phosphatase
c. N-terminal telopeptide
d. Collagen C-telopeptide
Correct answer is b.
10. Jig saw puzzle or mosaic pattern histologically is a feature of
a. Paget's disease
b. Osteosarcoma
c. Osteopetrosis
d. Fibrous dysplasia
Correct answer is a.
11. Which is the complication of Paget's disease?
a. Stress fractures
b. Secondary sarcomas
c. Both of the above
d. None of the above
Correct answer is c.
