A 42-year-old male patient was admitted to our hospital for planning autologous hematopoietic stem cell transplantation (auto-HSCT). He was diagnosed as multiple myeloma (IgG type Kappa) in 2003. His physical examination was normal with no important abnormality on laboratory evaluation. Chest radiography performed for routine evaluation prior to transplantation revealed a large, welldefined mass, that had obtuse angles with the chest wall consistent with extraparenchymal lesion superposed on second and third ribs. Also, there were multiple bony structures demonstrating changes of destructive effects of multiple myeloma. Computed tomography (CT)-guided biopsy was obtained from the mass by transthoracic fine-needle aspiration (FNAB) method. Biopsy was reported as extramedullary hematopoiesis (EMH) contrary to our expectation of multiple myeloma.