• Paget disease is a chronic metabolic bone
disorder characterized by imbalance
between bone resorption & new bone
• It is chronic metabolic bone disorder
characterized by abnormal osseous
It is common in England.
It is uncommon in Egypt and Middle East.
Age: it affects older persons.
Sex: more common in males.
• but recent hypothesis claims that it is due
to slow virus infection (due to the
presence of intranuclear inclusion bodies
in the osteoclasts).
Paget disease is divided into 3 phases:
1. Hot phase.
2. Intermediate phase.
3. Cool phase.
These 3 phases represent a continuum not
Incipien Osteoclas & cause bone
t phase ts
Osteoblas cause bone
d on bone
Osteoblas & cause new
• Monostotic or polystotic (more common) forms.
It is more common in the axial skeleton
• with the most common sites being
• pelvis, skull & spine.
Proximal long bones are also frequently affected
• with the most common among them proximal femur.
Paget disease of long bones begins in the subchondral
region of end & advances to the other end.
• Initial phase of increased osteoclastic
activity that affects both the cortex
and cancellous bone.
• Flat bones:
• There is no surrounding sclerosis (as there is
no osteoblastic activity in this phase)
• Long bone:
• candle flame or blade of grass appearance.
• Bone destruction accompanied by
new bone formation.
Cortical thickening and sclerosis of the iliopectineal and ischio-pubic lines, resulting in
obliteration of the tear drop.
• Typically demonstrates marked increased
uptake of radiotracer in all phases
The fatty bone
marrow is replaced
Yellow marrow fat signal
intensity is maintained or
even more bright as the
marrow space of pagetic
bone actually has more
fat than found in the
The fatty bone
(more obvious on
Contrast enhanced MRI
• Intracortical and speckled intramedullary
enhancement due to increased blood flow.