Identification of Aggressive Variants of Mantle Cell Lymphoma Based on Flow Cytometry

Document Type

Conference Proceeding

Publication Date

3-2018

Publication Title

Laboratory Investigation

Abstract

Background: Mantle cell lymphoma (MCL) is clinically and pathologically heterogeneous with highly variable outcome. Some patients have chronic/indolent course while others with pleomorphic or blastic variants have significantly shorter survival. The aim of our study is to explore if flow cytometry analysis can help with identification of aggressive MCL variants. Design: We retrospectively identified 48 nodal MCL diagnosed at our institution from 2010 to 2017. The original list mode data was reanalyzed. Median (Med), arithmetic mean (AMean), geometric mean (GMean) standard deviation (SD) and coefficient of variation (CV) of forward scatter (FSC) of all neoplastic B-cell and reactive T-cell events were collected. The numerical parameters and histograms of FSC were correlated with the clinical and pathological features. Student T-test and chi-squared test were used. Results: Out of all 48 cases, the average of FSC Med, AMean, and GMean for neoplastic B-cell events was 444, 440, and 417. The average of FSC Med, AMean, and GMean for reactive T-cell events was 409, 403, and 385. No overt statistical differences were detected in FSC Med, AMean, and GMean between neoplastic B-cell events and reactive T-cells (t-test, p>0.05). However, 15 cases of MCL showed very abnormal FSC histogram patterns: increased events of very low FSC, very high FSC or both (as shown in the figure of representative cases). These patterns are likely caused by lymphogranular bodies (low FSC) or unusually large lymphocytes (high FSC). Of these 15 cases, 10 (67%) were aggressive variants (5 pleomorphic and 5 blastic). In the remaining 33 cases, only 6 were classified as aggressive variants. Chi-squared test showed the difference was statistically significant (p=0.001) with relative risk of 3.7 and odds ratio of 9. Conclusions: MCL cases with very abnormal FSC histogram patterns are easily recognizable and likely to be aggressive. Therefore, we recommend evaluation of cytometric FSC parameters and histograms in all MCL cases. We also encourage further study of FSC in regards to clinical outcome (currently in progress at our institution) to determine if FSC may provide additional independent prognostic information that has not been previously reported.

Volume

98

Issue

Suppl 1

First Page

519

Comments

United States and Canadian Academy of Pathology (USCAP) 107th Annual Meeting, March 17-23, 2018, Vancouver, BC, Canada

Last Page

519

DOI

10.1038/labinvest.2018.13

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