Pathophysiology of myeloma bone disease.

Multiple myeloma is a tumor of terminally differentiated plasma cells that home to and expand in the bone marrow. It is the second most common hematologic malignancy, with approximately 16,000 new cases per year, and accounts for an estimated 11,000 deaths in the USA. It is the most common cancer to metastasize to bone, with up to 90% of patients developing bone lesions.