An approach for diagnosing plasma cell myeloma by three-color flow cytometry based on kappa/lambda ratios of CD38-gated CD138+ cells

Uta Nishiwaki,Toshiaki Hanafusa,Yuji Hirata,Yasuichiro Nishimura,Shoko Nakayama,Ayami Takayama,Yuki Masuda,Kazuki Iwaki,Taiji Yokote,Hidema Tanaka,Takuji Miyoshi,Toshiyuki Ikemoto,Motomu Tsuji,Toshikazu Akioka

doi:10.1186/1746-1596-7-131

Uta Nishiwaki, Toshiaki Hanafusa + Show 12 more

Open Access

https://doi.org/10.1186/1746-1596-7-131

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Abstract

BackgroundWorld 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.MethodsWe 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.ResultsPCM 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%.ConclusionsThree-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.Virtual slidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1568085959771735

Highlights

Plasma cell myeloma (PCM) is a bone marrow (BM)based, multifocal plasma cell (PC) neoplasm associated with the presence of M protein in serum and/or urine
We investigated the diagnostic value of an abnormal cytoplasmic kappa/lambda ratio of CD38-gated CD138+ PCs based on flow cytometry (FC) assessment
BM samples were obtained and examined from 23 patients who were recovering from inflammatory disorders and healthy people who were initially suspected as having hematological diseases and underwent examination for the same. (12 males and 11 females; age range, 29–81 years; mean ± standard deviation (SD), 62.5 ± 12.9 years)

Summary

Introduction

Plasma cell myeloma (PCM) is a bone marrow (BM)based, multifocal plasma cell (PC) neoplasm associated with the presence of M protein in serum and/or urine. World Health Organization (WHO) criteria are usually employed to diagnose PCM [1]. These criteria are based determined the diagnostic range for the kappa/lambda ratio that maximized the diagnostic sensitivity and specificity and minimized false-positive and false-negative results. World Health Organization (WHO) criteria are commonly used to diagnose plasma cell myeloma (PCM); 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

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