[How to diagnose a patient precisely as a myeloma patient?--Lots of problems during diagnostic process].

Typical multiple myeloma can be diagnosed precisely through lots of evaluations including the confirmation of the presence of increased clonal myeloma cells in bone marrow accompanied by monoclonal protein, cytopenia, bone diseases and renal disturbance. However, there still exists not a little difficulity during diagnostic process. In this article, representative problems are presented. Among them, the following issues are included; the confirmation or identification of minimal or 'masked' monoclonal proteins in several conditions (eg. myeloma following polyclonal hypergammaglobulinemic conditions), the differential diagnosis between Waldenström macroglobulinemia and IgM multiple myeloma, the differential diagnosis between MGUS with various complications and myeloma, the differential diagnosis of tumors in refractory phase of myeloma (eg. extramedullary plasmacytoma or transition to lympho -proliferative disorders from myeloma), and finally the interpretation of new M-component or oligo-clonal protein band in some periods after stem cell transplantation for myeloma.