Multiple myeloma (a malignant tumor) is usually a malignant hematologic disorder in which the body develops a malignant proliferation of monoclonal plasma cells. The concept, causes and symptoms, and treatment are explained below. 1. Multiple myeloma is characterized by an abnormal clonal proliferation of plasma cells in the bone marrow, which may be accompanied by monoclonal immunoglobulinemia, and may lead to severe damage to organs or tissues as the disease progresses. 2. Multiple myeloma may be caused by molecular and cytogenetic abnormalities, viral infections, radiation exposure, immune diseases, etc., which may lead to symptoms such as elevated blood calcium, bone pain, renal insufficiency and fever. 3. Multiple myeloma treatment drugs include bortezomib, cyclophosphamide, lenalidomide, dexamethasone and so on. Specific diagnosis and treatment should be carried out under the guidance of physicians.