AtlasBonePaget Disease of Bone

Bone Diseases

Paget Disease of Bone

aka Osteitis Deformans

Chronic disorder of accelerated, disorganised bone remodelling; jaw involvement causes progressive symmetrical enlargement, hypercementosis and denture non-fit.

Lab
↑ ALP only
Skull
Cotton wool
Rx
IV zoledronate

§ overviewOverview

Focal or multifocal disorder of bone remodelling characterised by increased and disorganised osteoclastic resorption followed by exuberant, disorganised osteoblastic bone formation.

§ icdICD Classification

M88

§ etiologyEtiology

  • 01Multifactorial: genetic (SQSTM1 mutation), possible paramyxovirus trigger
  • 02First-degree relatives 7× risk

§ epidemiologyEpidemiology

Adults >55 y; slight male predominance; higher prevalence in UK, Australia, New Zealand.

§ pathogenesisPathogenesis

Three phases: lytic (osteoclast-mediated) → mixed → sclerotic; disorganised bone is mechanically weak but hypervascular.

§ clinicalClinical Features

  • 01Progressive bone pain, deformity
  • 02Enlarging cranial vault (hat size increases)
  • 03Bilateral symmetrical jaw enlargement, spacing of teeth, denture becomes tight
  • 04Deafness (cranial nerve VIII compression)
  • 05High-output cardiac failure (rare)

§ radiographicRadiographic Features

  • 01Skull: 'cotton wool' patchy sclerosis
  • 02Jaw: hypercementosis, obliteration of PDL, loss of lamina dura
  • 03Ground-glass and mixed radiolucent-radiopaque appearance

§ labsLaboratory Findings

  • 01Markedly elevated serum alkaline phosphatase (isolated)
  • 02Normal calcium, phosphate, PTH
  • 03Increased urinary hydroxyproline and N-telopeptides

§ treatmentTreatment

  • 01Asymptomatic: monitor
  • 02Symptomatic: bisphosphonates (single-dose IV zoledronate preferred) — normalises ALP
  • 03Calcitonin (second line)
  • 04Analgesia, orthopaedic surgery for fractures
  • 05Dental: extractions difficult (dense bone, hypercementosis, bleeding); avoid elective surgery in active phase

§ complicationsComplications

  • 01Pathological fracture
  • 02Osteosarcoma (<1% but grim prognosis)
  • 03Cranial nerve palsies
  • 04Post-extraction haemorrhage or osteomyelitis

§ prognosisPrognosis

Generally good with bisphosphonate therapy; new hearing loss or increased pain warrants imaging to exclude sarcoma.

§ examKey Examination Points

  • 01Enlarging skull, ill-fitting dentures, isolated ALP rise

§ revisionQuick Revision Summary

  • 01Cotton-wool skull · isolated ALP · zoledronate

§ vivaBDS Viva Questions

  • 01Biochemical marker of Paget?
  • 02Complications of extractions in Paget?
  • 03Malignant transformation risk?

§ mcqsMCQs — Assessment (3)

Question 1

Classic biochemical finding:

Question 2

First-line pharmacotherapy:

Question 3

Malignant transformation to:

References

  1. Ralston SH. NEJM 2013

Draft — pending faculty review. Educational use only; verify against current guidelines and primary sources before clinical application.