|Discussion || |
Multiple myeloma (MM) is a malignant neoplasm of plasma cells that accounts for 1.8% of all cancers and ~17% of all hematological malignancies in the United States. It is most frequently diagnosed among people aged 65–74 years, with the median age being 69 years. The American Cancer Society has estimated close to 30,000 cases of myeloma newly diagnosed in 2017. The approximate death rate is 12,000 deaths per year.1 For a patient to be diagnosed with MM, they must have not only a plasma cell disorder but also end-organ damage attributable to the plasma cell disorder. This includes at least one of the CRAB criteria (hyper-Calcemia, Renal disease, Anemia, and Bone disease) classically used to define symptomatic MM. Anemia occurs in 73% of patients. Bone pain is common (60% of patients), and 50% of patients have an elevated serum creatinine. Renal disease results from light precipitated complexes obstructing the distal convoluted tubules. Other causes of renal disease include nephrocalcinosis, amyloidosis, heavy-chain disease, and light-chain disease. Hypercalcemia >11 mg/dL is present in 10% of patients. This requires hydration with isotonic saline and bisphosphonate therapy with zoledronic acid or pamidronate in moderate or severe cases. Calcitonin can also be used to rapidly reduce serum calcium levels. Other symptoms include fatigue (32%) and weight loss (20%). Because of immune dysfunction, patients are at risk for infections. About 7%–18% of patients may present with extramedullary plasmacytomas. Less common symptoms include fever, splenomegaly, hepatomegaly, and lymphadenopathy.