Bone marrow trephine biopsies from 2012 (a–d) and 2018 (e–h), respectively. The nodular lymphoid infiltrates (a) are CD20 positive (b) and surrounded by κ positive plasma cells (c), typical for CAD. In other areas, there are small focal aggregates of λ positive plasma cells (d), consistent with MGUS. In the 2018 biopsy, there is extensive plasma cell infiltration (e), consistent with MM. CD20 staining (f) shows remaining CD20 positive CAD infiltrates. The MM is IgA positive (g), whereas the CAD infiltrates are IgM positive (h).