Gastrointestinal bleeding as initial presentation of extramedullary plasma cell neoplasms: A case report and review of the literature

Figure 3 Small bowel plasmablastic myeloma staining. A: Small bowel plasmablastic myeloma positive CD38 staining. CD38 is routinely used for identification of plasma cell neoplasms and stains primarily the membrane due to expression of the transmembrane protein cyclic ADP ribose hydrolase; B: Same specimen positive for CD 138 staining. CD138 is a transmembrane heparan sulphate proteoglycan (syndecan-1). CD138 staining is positive in normal B-cell precursors and plasma cells, along as plasmablastic lymphomas and myelomas; C: Same specimen positive for MUM-1 (Multiple Myeloma-1) nuclear stain. MUM-1 is a nuclear transcriptional factor that is expressed in late plasma cell directed stages of B cell differentiation and also in activated T cells; D: Small bowel plasmablastic myeloma staining positive for Ki 67 (MIB-1). MIB-1 is the IgG1 antibody against Ki 67 which can be detected in the cellular nucleus and is a marker of cell proliferation. Strong expression of the nuclear marker Ki 67 with MIB-1 staining indicates high proliferation rate and is a sign of clinical aggressiveness.