MSH: A malignancy of mature PLASMA CELLS engaging in monoclonal immunoglobulin production. It is characterized by hyperglobulinemia, excess Bence-Jones proteins (free monoclonal IMMUNOGLOBULIN LIGHT CHAINS) in the urine, skeletal destruction, bone pain, and fractures. Other features include ANEMIA; HYPERCALCEMIA; and RENAL INSUFFICIENCY.,CSP: malignant neoplasm of plasma cells usually arising in the bone marrow and manifested by skeletal destruction, bone pain, and the presence of anomalous immunoglobulins.,MEDLINEPLUS: Multiple myeloma is a cancer that begins in plasma cells, a type of white blood cell. These cells are part of your immune system, which helps protect the body from germs and other harmful substances. In time, myeloma cells collect in the bone marrow and in the solid parts of bone. No one knows the exact causes of multiple myeloma, but it is more common in older people and African-Americans. Early symptoms may include Bone pain, often in the back or ribs Broken bones</