Multiple myeloma is best described as:

• A. Lymphoproliferative disease of T cells
• B. Cancer of plasma cells characterized by increased antibody concentration
• C. Lymphoproliferative disease resulting in a decrease in antibody production
• D. Cancer of monocytes with increased kappa and lambda chain synthesis

Answer: (B)

Multiple myeloma arises when malignant plasma cells clonally expand in the bone marrow and secrete a single type of immunoglobulin. This creates an increased level of a specific antibody—a monoclonal immunoglobulin—in the blood (and often detectable as light chains in urine, known as Bence Jones proteins). That monoclonal antibody production by cancerous plasma cells is the defining feature, making the description “cancer of plasma cells characterized by increased antibody concentration” the best fit. It's not a T-cell lymphoproliferative disorder and not a monocyte cancer, and while overall antibody diversity can be reduced because normal plasma cells are suppressed, the hallmark is the rise of a single monoclonal antibody.