Osteolytic bone lesions of MM

Osteolytic bone lesions of MM are areas of destroyed bone that form when the cancerous plasma cells of multiple myeloma activate bone-resorbing cells and suppress new bone formation. The skeleton is the site affected most often, particularly the spine, pelvis, ribs and skull. Myeloma cells drive osteoclasts to break down excess bone while inhibiting the osteoblasts that rebuild it; steroid treatment further reduces bone density. Typical features are back or rib pain and easily broken bones; vertebral collapse can compress the spinal cord, and calcium released from bone can cause confusion, thirst and fatigue. Lesions are found with imaging, including skeletal x-ray surveys, MRI, and CT or PET scans, alongside marrow biopsy. Bisphosphonates, which inhibit osteoclasts, are recommended to slow bone loss, ease pain and reduce fractures; radiation therapy treats spinal lesions, and the myeloma needs separate anticancer treatment.