A 60-year-old woman has a pathological fracture through a lytic lesion of the proximal femur. MRI shows multiple lesions in the pelvis, spine, and ribs as well. Serum alkaline phosphatase is normal but serum calcium is elevated and serum protein electrophoresis shows an M-spike. The bone lesion is most consistent with:

• A Metastatic breast carcinoma
• B Paget's disease of bone with secondary sarcomatous change
• C Hyperparathyroid brown tumours
• D Multiple myeloma ✓

Explanation

The combination of multiple purely lytic lesions, normal alkaline phosphatase (no osteoblastic response), hypercalcaemia (from osteoclast activation via RANKL), and an M-spike on SPEP is pathognomonic for multiple myeloma. Metastatic breast cancer can be lytic or mixed, but would not produce an M-spike. Paget's disease shows markedly elevated ALP; sarcomatous change shows a single destructive lesion. Hyperparathyroidism brown tumours cause subperiosteal resorption and elevated PTH rather than an M-spike.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.