A study published in November 2022 and reported in the Journal of Clinical Oncology by Jelinek et al. revealed that a level of 2% of circulating plasma cells (CTCs) would indicate PCL-like multiple myeloma [4]. CTCs look like marrow plasma cells; however, they don't have CD56 expression, while MM cells with PCL have more incidence of monosomy 13, Del 17p, and defects in chromosomes 1, 1q21, and others. This evidence concerns the gene NCAM1 and plasma cell leukemia.