<prompt> The following is the least useful investigation in multiple myeloma?ESRX-RayBone scanBone marrow biopsy  <response>: Multiple myeloma is associated with negative bone scan or cold lesions. The bone scan measures the osteoblastic activity. In multiple myeloma, the osteoblasts doesnt react much to bone destruction. Bone scans are least useful for diagnosing multiple myeloma because the cytokines secreted by myeloma cells suppress osteoblastic activity. Ref: Harrisons Principles of Internal Medicine, 17th Edition, Page 703-705; 16th 658, 659; Davidsons principles and practice of Medicine, 20th Edition, Chapter 24, Page 1052-1054 