Bone Tumors: Multiple Myeloma.

Multiple myeloma (MM) is a malignancy of bone marrow plasma cells that produce abnormal immunoglobulins. It is the second most common hematologic cancer and typically is diagnosed in individuals ages 65 to 74 years. MM is the final stage in a continuum that starts with monoclonal gammopathies of undetermined significance (MGUS), a premalignant condition characterized by production of abnormal immunoglobulins. Patients with MGUS often are asymptomatic but can experience clinical manifestations such as recurrent infections. Standard care for patients with MGUS is monitoring for progression to MM, which occurs in approximately 1% of patients per year. Some patients experience an intermediate phase called smoldering multiple myeloma (SMM), characterized by higher levels of abnormal immunoglobulins and more plasma cells in the bone marrow. Most cases of SMM progress to MM over 15 years. MM has specific diagnostic criteria with defining clinical characteristics: hypercalcemia, renal insufficiency, anemia, and bone lesions (ie, CRAB criteria). MM management involves corticosteroids, chemotherapy, and autologous stem cell transplantation, as well as addressing complications including renal disease, hypercalcemia, bone disease, pain, hyperviscosity syndrome, infections, thromboembolic events, and anemia. MM is incurable. The survival time range of patients with newly diagnosed MM is 5 to 7 years.