The histological hallmark that distinguishes osteomalacia from osteoporosis on undecalcified bone biopsy is:

• A Increased osteoclastic resorption lacunae with marrow fibrosis
• B Thinning of trabeculae with preserved mineralization of remaining bone
• C Widening of unmineralized osteoid seams with delayed mineralization ✓
• D Mosaic pattern of lamellar bone with cement lines

Explanation

Osteomalacia is a disorder of mineralization: osteoid volume and seam width are increased and the mineralization lag time is prolonged, demonstrable by double tetracycline labelling. Osteoporosis shows reduced bone quantity with normally mineralized, structurally thinned trabeculae, which defines option B. Mosaic cement lines define Paget disease, killing option D, and increased resorption lacunae with fibrosis define hyperparathyroid bone disease, killing option A.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.