CD79A and plasma cell myeloma: Up to now, the definition of SMM has gone through a series of developments, based on the International Myeloma Working Group (IMWG) diagnostic criteria published in 2014, SMM is defined by serum monoclonal protein (IgG or IgA) ≥30 g/L or urinary monoclonal protein ≥500 mg per 24 h and/or clonal bone marrow plasma cells 10–60% and with the absence of myeloma defining events or amyloidosis [2].