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Paget's Disease of Bone — RACP Adult Medicine MCQ

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ModerateGeneral Internal MedicinePaget's Disease of BoneRACP Adult Medicine

A 75-year-old man presents with progressive bilateral hearing loss and a conductive component on audiometry. Otoscopy is normal. Bone density is normal. Serum ALP is markedly elevated at 850 U/L with normal calcium and phosphate. A technetium-99m bone scan shows increased uptake in the skull. What is the most likely diagnosis?

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Correct answer: D — Fibrous dysplasia

Markedly elevated ALP with normal calcium and phosphate, increased skull uptake on bone scan, and hearing loss is characteristic of Paget's disease affecting the skull. Hearing loss in Paget's results from involvement of the temporal bone (ossicular and cochlear involvement). The isolated elevated ALP (with normal calcium and phosphate) distinguishes Paget's from metastatic bone disease (which often has hypercalcaemia). Treatment with bisphosphonates (zoledronic acid single infusion) is indicated.

Reference: eTG – 2025 – Rheumatology; Endocrine Society – 2014 – Paget's Disease Guidelines