MYOM2 and plasma cell myeloma: An intermediate stage between MGUS and MM is smoldering multiple myeloma (SMM), characterized by a serum M-protein ≥3.0 g/dL or a urinary M-protein ≥500 mg per 24 hours and/or a clonal bone marrow plasma cell infiltration of 10-60%, in the absence of end-organ damage (CRAB) or an involved:uninvolved serum FLC ratio of ≥100 or ≤0.01, and with ≤1 focal lesions on magnetic resonance imaging (MRI) (10).