On plain X-ray, a lesion shows 'ground-glass opacity with a thin sclerotic rim' (rind sign) in the proximal femoral shaft. The most likely diagnosis is:

• A Non-ossifying fibroma
• B Simple bone cyst
• C Enchondroma
• D Fibrous dysplasia ✓

Explanation

Fibrous dysplasia classically appears as a ground-glass or hazy matrix lesion with a thin surrounding sclerotic rim ('rind sign' or 'thick rind' in long-standing cases), most often in the metaphysis or diaphysis of long bones. The ground-glass opacity reflects replacement of normal bone by fibro-osseous tissue lacking trabecular architecture. Non-ossifying fibroma is eccentric, cortically based, with scalloped sclerotic margins but no internal matrix. Simple bone cysts are purely lytic with pathological fracture predilection.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.