Plain radiograph of the pelvis in a 55-year-old with bone pain shows patchy sclerosis and lysis with cortical thickening, enlargement of the pelvic bones, and a coarsened 'cotton-wool' trabecular pattern. Serum alkaline phosphatase is markedly elevated. Which radiographic sign in the skull would clinch the diagnosis?

• A Hair-on-end pattern
• B Beaten copper skull
• C Wormian bones
• D Cotton-wool appearance of the calvarium with osteoporosis circumscripta ✓

Explanation

Paget's disease of bone classically shows cotton-wool sclerosis in the skull vault (mixed lytic-sclerotic phase) and osteoporosis circumscripta (pure lytic phase starting at the frontal/occipital bone). Combined with bony expansion and elevated ALP, this is diagnostic. Hair-on-end is seen in haemolytic anaemias (thalassaemia, sickle cell). Beaten copper skull suggests raised intracranial pressure. Wormian bones occur in osteogenesis imperfecta and hypothyroidism.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.