Multiple Myeloma
Multiple myeloma is a plasma cell malignancy that exists on a spectrum with monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma. Malignant plasma cells produce a monoclonal immunoglobulin protein (M-protein) that leads to end-organ damage. The diagnosis of MGUS is made if the patient has a detectable M-protein <3 g/dL or bone marrow biopsy revealing <10% clonal plasma cells, without end-organ damage. If the M-protein increases to >3 g/dL or bone marrow plasma cells increase to >10% without end-organ damage, the patient has smoldering myeloma. Once the patient has end-organ damage, including hypercalcemia, anemia, renal impairment, or bone disease (CRAB criteria), the patient has multiple myeloma. Work-up for multiple myeloma includes examination of serum and urine for aberrant proteins via protein electrophoresis, immunofixation, and assessment of free light chains. Bone marrow biopsy with cytogenetic analysis and fluorescence in situ hybridization (FISH) determine bone marrow involvement, and imaging with skeletal survey, CT, or MRI can detect bone lesions. Patients with MGUS and smoldering myeloma do not require immediate treatment but are at increased risk for progression to symptomatic multiple myeloma and therefore need close monitoring. Symptomatic multiple myeloma is treated with combination systemic chemotherapy with the potential for autologous stem cell transplant in eligible patients. The increased number and efficacy of therapeutic options for multiple myeloma have led to significant improvement in prognosis..
