title: An approach for diagnosing plasma cell myeloma by three-color flow cytometry based on kappa/lambda ratios of CD38-gated CD138(+) cells.
abstract: BACKGROUND
  World Health Organization (WHO) criteria are commonly used to diagnose plasma cell myeloma (PCM); however, these criteria are complex and require several laboratory parameters. For differentiating reactive plasmacytosis from clonal plasma cell (PC) neoplasms such as PCM, it is important to accurately determine the expression of cytoplasmic immunoglobulin light chains.
  
  
  METHODS
  We retrospectively analyzed the records of 27 selected patients with PCM who underwent bone biopsies for confirmative diagnosis according to WHO criteria. Twenty-three controls were also investigated. In the present study, all the samples were analyzed using flow cytometry (FC) in the side scatter vs. CD38 histogram mode, and the CD38-gated PC population was identified. Bivariate histograms of CD138/kappa and CD138/lambda were assessed, and the ratios of dual-positive cells to the CD138(+) PC population were calculated. The kappa/lambda ratio was defined as the ratio of CD138/kappa to CD138/lambda.
  
  
  RESULTS
  PCM cells were distinguished from normal PCs using cutoff levels between 0.76 and 1.5, at a sensitivity of 96.3% and specificity of 95.7%.
  
  
  CONCLUSIONS
  Three-color FC analysis is simple to perform and inexpensive, with clinically relevant data obtained soon after the completion of FC measurements. The detection of the cytoplasmic kappa/lambda ratio of CD38-gated CD138(+) PCs may be a useful tool in the diagnosis of PCM. To the best of our knowledge, this report represents the first diagnostic assessment of the cytoplasmic kappa/lambda ratio in CD38-gated CD138+ PCs using FC analysis. This method may help in more simple, efficient, rapid, and accurate diagnosis of PCM.
  The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1568085959771735.
authors.affiliation: First Department of Internal Medicine (I), Osaka Medical College, 2-7 Daigakumachi, Takatsuki City, Osaka, 569-0801, Japan. in1304@poh.osaka-med.ac.jp
authors.forename: Shoko
authors.initials: S
authors.lastname: Nakayama
authors.forename: Taiji
authors.initials: T
authors.lastname: Yokote
authors.forename: Yuji
authors.initials: Y
authors.lastname: Hirata
authors.forename: Kazuki
authors.initials: K
authors.lastname: Iwaki
authors.forename: Toshikazu
authors.initials: T
authors.lastname: Akioka
authors.forename: Takuji
authors.initials: T
authors.lastname: Miyoshi
authors.forename: Ayami
authors.initials: A
authors.lastname: Takayama
authors.forename: Uta
authors.initials: U
authors.lastname: Nishiwaki
authors.forename: Yuki
authors.initials: Y
authors.lastname: Masuda
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Ikemoto
authors.forename: Hidema
authors.initials: H
authors.lastname: Tanaka
authors.forename: Yasuichiro
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Motomu
authors.initials: M
authors.lastname: Tsuji
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Hanafusa
mesh_terms: D051997:ADP-ribosyl Cyclase 1 / Q000032:analysis*; D014408:Biomarkers, Tumor / Q000032:analysis*; D005434:Flow Cytometry / Q000379:methods*; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000032:analysis*; D007146:Immunoglobulin lambda-Chains / Q000032:analysis*; D016130:Immunophenotyping / Q000379:methods*; D008562:Membrane Glycoproteins / Q000032:analysis*; D009101:Multiple Myeloma / Q000175:diagnosis* / Q000276:immunology; D010950:Plasma Cells / Q000276:immunology*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D053668:Syndecan-1 / Q000032:analysis*
chemical_list: D014408:Biomarkers, Tumor; D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains; D008562:Membrane Glycoproteins; C508241:SDC1 protein, human; D053668:Syndecan-1; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1