ABSTRACT
A 76 year-old female who was diagnosed with multiple myeloma (IgG, lambda) had received bortezomib, melphalan and prednisolone as first-line treatment. After completing six cycles of chemotherapy, her serum monoclonal protein level decreased from 7.28 g/dL to 0.65 g/dL, indicating a partial response. However, at the next scheduled visit she complained of slowly progressing dyspnea. On chest X-ray, newly developed pleural effusion was found, and rapidly progressing extramedullary plasmacytoma was detected in the anterior mediastinum on chest computerized tomography. However, there was no change in her serum monoclonal protein level. In Korea, extramedullary involvement is encountered in 5% of patients with multiple myeloma. However, evaluation of treatment response using solely the serum monoclonal protein level may not accurately reflect disease status in these patients.