Paget's Disease of Bone

Question 1

Definition

Answer 1

Characterised by excessive bone remodelling at one (monostotic) or more (polyostotic) sites resulting in bone that is structurally disorganised

Question 2

Aetiology

Answer 2

· UNKNOWN

· Genetic factors and viral infection may play a role

· Excessive bone resorption by abnormally large osteoclasts is followed by increased bone formation by osteoblasts in a disorganised fashion

· This results in an abnormal pattern of lamellar bone

· Marrow spaces are filled by an excess of fibrous tissue with a marked increase in blood vessels

Question 3

Epidemiology

Answer 3

· Common in ELDERLY

· 3% of > 50 yrs
· 10% of > 80 yrs

· Males = Females

Question 4

Presenting symptoms

Answer 4

· May be ASYMPTOMATIC

· May present with insidious onset pain, which is aggravated by weight bearing and movement

· Headaches

· Deafness

· Increasing skull size

Question 5

Signs on physical examination

Answer 5

· Bitemporal skull enlargement with frontal bossing (prominent, protruding forehead)

· Spinal kyphosis

· Anterolateral bowing of femur, tibia or forearm

· Skin over the affected bone may be warm (due to increased vascularity)

· Sensorineural deafness (due to compression of vestibulocochlear nerve)

Question 6

Investigations (radiograph)

Answer 6

· Bone Radiographs

o Enlarged, deformed bones

o Lytic and sclerotic appearance

o Lack of distinction between cortex and medulla

o Skull changes:
· Osteoporosis circumscripta
· Enlargement of frontal and occipital areas
· Cotton wool appearance

Question 7

Investigations (other)

Answer 7

· Bloods
o High ALP
o Ca2+ and phosphate = NORMAL

· Bone Scan
o Assesses extent of skeletal involvement
o Pagetic bone lesions appear as areas with markedly increased uptake

· Resorption Markers
o Monitors disease activity
o Check urinary hydroxyproline