title: Expression of CD19 and lack of miR-223 distinguish extramedullary plasmacytoma from multiple myeloma.
abstract: OBJECTIVE
  Extramedullary plasmacytoma (EMP) and multiple myeloma (MM) are both plasma cell (PC) tumours that are usually distinguished by clinical manifestations, but not by histopathological examination alone. However, EMP may express B-cell markers, such as CD79a and CD20, and MM may express germinal centre B-cell (GCBC)-associated microRNAs, such as miR-93 and miR-181b. Down-regulation of miR-30a or up-regulation of miR-223 is associated with the transition from GCBCs into PCs or memory B-cells, respectively. We studied B-cell markers and microRNAs to establish criteria that could distinguish EMP from MM.
  
  
  RESULTS
  Immunostains for the B-cell markers CD19, CD20, CD79a and PAX5 were performed. Expression levels of microRNAs 30a, 93, 181b and 223 were measured by real-time reverse transcription polymerase chain reactions. 73% of EMPs expressed CD19 whereas MM cases were negative. EMP and MM had similar levels of miR-30a, miR-93, and miR-181b, but EMP lacked expression of miR-223.
  
  
  CONCLUSIONS
  The presence of CD19 and lack of miR-223 suggested aberrant B-cell differentiation in EMP. Although the underlying mechanism for this differential expression was unclear, a CD19(+) /miR-223(-) phenotype could be used to distinguish EMP from the CD19(-) /miR-223(+) phenotype of MM.
authors.affiliation: Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Shan-Chi
authors.initials: SC
authors.lastname: Yu
authors.forename: Shee-Uan
authors.initials: SU
authors.lastname: Chen
authors.forename: Wen
authors.initials: W
authors.lastname: Lu
authors.forename: Ting-Yun
authors.initials: TY
authors.lastname: Liu
authors.forename: Chung-Wu
authors.initials: CW
authors.lastname: Lin
mesh_terms: D018941:Antigens, CD19 / Q000378:metabolism*; D001402:B-Lymphocytes / Q000378:metabolism / Q000473:pathology; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002454:Cell Differentiation; D003937:Diagnosis, Differential; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000378:metabolism*; D008875:Middle Aged; D009101:Multiple Myeloma / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D010641:Phenotype; D010954:Plasmacytoma / Q000175:diagnosis* / Q000378:metabolism* / Q000473:pathology; D011379:Prognosis; D012189:Retrospective Studies
chemical_list: D018941:Antigens, CD19; D014408:Biomarkers, Tumor; D035683:MicroRNAs; C525067:MIR223, human