Paget's Disease of Bone

Question 1

What is Paget’s disease on bone?

Answer 1

refers to a disorder of bone turnover

there is excessive bone turnover (formation and reabsorption) due to excessive activity of both osteoblasts and osteoclasts

This excessive turnover is not coordinated, leading to patchy areas of high density (sclerosis) and low density (lysis)

This results in enlarged and misshapen bones with structural problems that increase the risk of pathological fratures

It particularly affects the axial skeleton (the bones of the head and spine)

Question 2

Presentation of Paget’s disease of bone

Answer 2

typically affects older adults. It presents with:

Bone pain
Bone deformity
Fractures
Hearing loss can occur if it affects the bones of the ear

Question 3

X ray findings in Paget’s disease of bone

Answer 3

Bone enlargement and deformity

“Osteoporosis circumscripta” describes well defined osteolytic lesions that appear less dense compared with normal bone

“Cotton wool appearance” of the skull describes poorly defined patchy areas of increased density (sclerosis) and decreased density (lysis)

“V-shaped defects” in the long bones are V shaped osteolytic bone lesions within the healthy bone

Question 4

Biochemistry of Paget’s disease

Answer 4

Raised alkaline phosphatase (and other LFTs are normal)

Normal calcium

Normal phosphate

Question 5

Management of Paget’s disease of bone?

Answer 5

Bisphosphonates are the main treatment - generally very effective, they interfere with osteoclast activity and seem to restore normal bone metabolism. they improve symptoms and prevent further abnormal bone changes

Other measures include:
- NSAIDs for bone pain
- Calcium and vitamin D supplementation, particularly whilst on bisphosphonates
- Surgery is rarely required for fractures, severe deformity or arthritis

Monitoring involves check the serum alkaline phosphatase (ALP) and reviewing symptoms. Effective treatment should normalise the ALP and eliminate symptoms.

Question 6

Complications of Paget’s disease of bone

Answer 6

Two key complications to remember are:

Osteogenic sarcoma (osteosarcoma)
Spinal stenosis and spinal cord compression

Osteosarcoma is a type of bone cancer with a very poor prognosis. It presents with increased focal bone pain, bone swelling or pathological fractures. The risk is increased in Paget’s disease and patients need to be followed up to detect it early. They can usually be seen on a plain xray.

Spinal stenosis may occur where deformity in the spine leads to spinal canal narrowing. If this presses on the spinal nerves it causes neurological signs and symptoms. This is diagnosed with an MRI scan and is often treated effectively with bisphosphonates. Surgical intervention may be considered.