Centrin staining and centrosome amplification in healthy donors and patients with monoclonal gammopathies. (A) Majority of normal PCs had no centrin signals compared with clonal plasma cells (P < .001), whereas centrosome amplification was almost exclusively seen in clonal PCs (P < .001). (B) Percentage of cIg-positive PCs with centrosome amplification increased with more advance stage of PC proliferation.