Multiple myeloma is a disease that affects the bone marrow of the bones and is a cancer of the plasma cells. In multiple myeloma, mutated plasma cells in bone marrow grow and produce an abnormal protein. (The mutated (i.e., monoclonal) plasma cells divide and grow and crowd out the normal bone marrow, causing a patient to become anemic and at risk of infections.) In turn, this abnormal protein produces osteoclast-activating factor, thus activating osteoclasts, which themselves cause lysis of bone cells. Lysis is destruction of a cell by breaking its cell membrane. Lysis of bone cells produces holes in bones. These areas are sometimes referred to as being "punched out" areas. Of course, bones that have holes in them are weaker and subject to breaking spontaneously. Osteoclasts are the cells in the bone that normally help remodel bones in the normal homeostasis of bones. Bone cells are constantly destroyed (by osteoclasts) and created (by osteoblasts). In multiple myeloma, the ratio of osteoclasts to osteoblasts is disrupted such that osteoclasts far outnumber osteoblasts.
Multiple myeloma medical expert witness specialties include oncology, hematology, pediatric, oncology, pediatric hematology, and pathology.