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Paget disease extent — SCE Rheumatology MCQ

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HardMetabolic bone diseasePaget disease extentSCE Rheumatology

A 69-year-old man is found to have a persistently raised serum alkaline phosphatase concentration. Gamma-glutamyl transferase, adjusted calcium, phosphate, parathyroid hormone and 25-hydroxyvitamin D are normal. A skull radiograph shows cortical thickening, bone expansion and mixed lytic and sclerotic change characteristic of Paget disease of bone. He also reports progressive left-sided hearing impairment. Which investigation is most appropriate to establish whether he has monostotic skull disease or additional metabolically active skeletal sites?

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Correct answer: B — Whole-body radionuclide bone scintigraphy

Whole-body radionuclide bone scintigraphy is the best investigation to define the extent of metabolically active Paget disease and identify clinically occult sites, distinguishing monostotic from polyostotic disease. Targeted radiographs establish characteristic structural changes, while scintigraphy maps active disease throughout the skeleton. Bone-specific alkaline phosphatase can quantify turnover when total ALP is uninformative but cannot localise disease. Pure-tone audiometry would characterise the hearing deficit, and temporal-bone CT may delineate local osseous complications; neither assesses whole-skeleton extent. MRI is useful when a neurological, skull-base or alternative internal auditory canal lesion is suspected, but it is not the standard staging investigation for Paget disease.

Reference: Ralston SH et al. Diagnosis and Management of Paget's Disease of Bone in Adults: A Clinical Guideline. Key recommendation on defining disease extent. Journal of Bone and Mineral Research. 2019;34:579–604. https://pubmed.ncbi.nlm.nih.gov/30803025/