[The pathology of smoldering multiple myeloma].

The precursor states (named as monoclonal gammopathy of undetermined significance [MGUS] and smoldering multiple myeloma [SMM]) consistently exist before symptomatic multiple myeloma is diagnosed. After approximately 30 years have passed since Kyle et al. advocated MGUS and SMM for the first time, the pathology and prognosis of these diseases have been clarified considerably. Recently, the safety and efficacy of the early treatment for the patients with high risk SMM are shown. In this article, the current understanding of the pathology of SMM as well as MGUS including the diagnosis, prognosis and treatment is reviewed.