Light-Chain Multiple Myeloma: A Diagnostic Challenge

Light-chain multiple myeloma (LCMM) is a less frequent type of multiple myeloma (MM), with a more aggressive course and poorer prognosis. It is characterized by the inability of the malignant plasma cells to produce heavy chains, resulting in the exclusive production of light chains. Therefore, no M-spike is visible in serum protein electrophoresis. We described the case of a 67-year-old female who presents to the emergency department with anemia, severe renal insufficiency, and multiple lytic bone lesions. After three days, the diagnosis of kappa light chain multiple myeloma was made in a patient with elevated serum and urinary kappa light chains and a bone marrow aspirate with 21.7% of atypical plasma cells. The rapid diagnosis allowed prompt referral to a specialized multiple myeloma center and early initiation of treatment.