History and exam

Key diagnostic factors

common

family history of PDB

A positive family history is strongly associated with the condition.

The relative risk of developing the condition is as high as 7 in first-degree relatives of people diagnosed with PDB.[10]

asymptomatic

Asymptomatic in most patients.[3][37]

The disease may be identified incidentally by characteristic radiological or liver function test results.

Other diagnostic factors

common

femoral, pelvis, and/or skull involvement

PDB can affect any bone segment, but 75% of patients have localised disease of the femur and/or pelvis.[38]

Approximately 37% of people have disease affecting the skull.[39]

long-bone or back pain

Pain occurs because of the high metabolic activity or deformation of the affected bones.

Back pain can be caused by spinal stenosis due to narrowing of the spinal canal or by the blood-supply-steal mechanism.[23][24]

pathological fracture

Occurring in weakened pagetoid bone.

May present with pain.

bony deformities (e.g., frontal bossing, prognathism, bone bowing)

Frontal bossing (affected patients may notice that they have had to increase the size of their headwear).

Prognathism (affected patients note progressive enlargement of the mandible).

increased local temperature

Very common due to increased metabolic activity.

hearing loss

Common in skull involvement. Accompanied by facial pain.[27]

uncommon

facial pain

Not very common, but can occur in skull involvement affecting cranial nerve V.

loosening teeth or disturbance in chewing

May occur when the facial bones are affected leading to maxillary or jaw bone enlargement and malocclusion.[26]

isolated raised alkaline phosphatase

Serum alkaline phosphatase is usually elevated in PDB, although patients with limited disease extension may have normal alkaline phosphatase (15%).[32]

Risk factors

strong

family history of PDB

Familial clustering suggests that PDB may have an autosomal dominant pattern of inheritance with variable penetrance.[9]

The relative risk of developing the condition is as high as 7 in first-degree relatives of people diagnosed with PDB.[10]

Mutation in a gene called sequestosome 1 (on the long arm of chromosome 5) has been found in studied families with PDB, although it has also been found in non-familial sporadic cases of PDB too.[3][25]

Different variants in loci of several genes (i.e., CSF1, TNFRSF11A, and OPTN) have been highly associated with the development of PDB in subjects that are noncarriers of the sequestosome 1 mutation.[11]

Two other genes, the RANK and the VCP genes, have been weakly linked to PDB.

age >50 years

The mean age of onset is 55 years old.[7]

weak

male sex (45- to 74-years age group)

Although there is an equal distribution among men and women in other groups, there is a slight male predominance in the 45- to 74-years age group.[7]

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