**2. Main features of Multiple Myeloma**

Multiple myeloma is the second most common hematological cancer and represents 10% of all hematological malignancies and 1 % of all cancers. The annual incidence of the disease in the US is 4 in 100,000. Approximately 100,000 new cases of MM are diagnosed each year worldwide [1]. MM accounts for 1% of all cancer-related deaths (approximately 72,000 deaths annually). The vast majority of the patients diagnosed with MM are 70-80 years old. MM is characterized by unregulated plasma cell proliferation in the bone marrow. These malignant plasma cells produce and secrete abnormal immunoglobulin (Ig) or immunoglobulin frag‐ ments. The monoclonal lg in the sera can cause hyperviscosity and this is one of the major symptoms of the disease. Clinical features and typical laboratory findings of MM include fatigue, bone pain, osteolythic bone lesions, pathologic bone fracture, anemia, hypercalcaemia, renal insufficiency, elevation of monoclonal Ig in the sera and/or in the urine and elevated erythrocyte sedimentation rate. The etiology of MM is unknown but aside from several environmental factors that are suspected, more and more cytogenetic alterations involved with the oncogenic process are detected [2,3].
