Two-site evaluation of a new workflow for the detection of malignant cells on the Sysmex XN-1000 body fluid analyzer

Serous body fluid evaluation using the new automated haematology analyser Mindray BC-6800Plus

OBJECTIVES

Cellular analysis of body fluids (BF) has clinical relevance in several medical conditions. The objective of this study is twofold: (1) evaluate the analytical performance of the BF mode of Mindray BC-6800 Plus compared to manual counts under microscopy and (2) analyse if the high-fluorescent cell counts provided by the analyser (HF-BF) are useful to detect malignancy.

METHODS

A total of 285 BF was analysed: 250 corresponding to patients without neoplasia and 35 to patients with malignant diseases. Manual differential counts were performed in BF with ≥250 cells/μL. Percentages and absolute counts were obtained on the BC-6800Plus for total nucleated cells (TC-BF), mononuclear, polymorphonuclear and HF-BF. Statistical analysis was performed using Mann-Whitney U-test, Spearman's correlation, Passing-Bablok regression, Bland-Altman graph and ROC curve.

RESULTS

To compare manual and automatic total cell counts, samples were divided in three groups: <250, 250-1,000 and >1,000 cells/μL. Correlation was good in all cases (r=0.72, 0.73 and 0.92, respectively) without significant differences between both methods (p=0.65, 0.39 and 0.30, respectively). The concordance between methods showed values of 90%. Considering malignant samples, median HF-BF values showed significant higher values (102 cells/μL) with respect to non-malignant (4 cells/μL) (p<0.001). The cut-off value of 8.5 HF-BF/μL was able to discriminate samples containing malignant cells showing sensitivity and specificity values of 89 and 71%, respectively. Considering both, HF-BF and TC-BF values, sensitivity and specificity values were 100 and 53%, respectively.

CONCLUSIONS

This study reveals that the Mindray BC-6800Plus offers an accurate and acceptable performance, showing results consistent with the manual method. It is recommended to consider both HF-BF and TC-BF values for the screening of the microscopic evaluation to ensure the detection of all malignant samples.

Clinical application of an algorithm to screen for malignant cells in body fluids using an automated hematology analyzer

INTRODUCTION

The detection of malignant cells in body fluids (BF) with an automated hematology analyzer has been proposed as an alternative to morphological examination owing to its various advantages; however, its limitations have also been highlighted. In this study, we devised a practical algorithm to screen for malignant cells in BFs using an automated hematology analyzer.

METHODS

A total of 558 BF samples, including 232 cerebrospinal fluid (CSF) samples and 326 non-CSF samples, were consecutively collected. Thereafter, the results obtained using the BF mode of Sysmex XN-350 (Sysmex, Kobe, Japan) were compared with the cytological diagnosis. A cutoff was also established to screen for malignant cells using receiver operating characteristic (ROC) curve analysis based on the final clinical judgment.

RESULTS

The automated hematology analyzer showed a moderate correlation or good agreement with the existing cytological diagnosis. Further, of the ROC curves for detecting malignant cells, the absolute value of highly fluorescent cells on BF (HF-BF) in total body fluids showed the highest area under the curve (0.85 [95% confidence interval 0.82-88], p < .0001, Youden index >7×10⁶ /L, sensitivity 93%, and specificity 65%).

CONCLUSION

An automated hematology analyzer could function as a complement to cytological examination. We propose a practical and comprehensive algorithm for cytological examination that requires low- and high-resolution microscopy based on the absolute value of HF-BF in BF samples suspected of malignancy. This algorithm can more usefully detect malignant cells while taking advantage of the automated analyzer and cytological examination.

Automated cell count in body fluids: a review

Body fluid cell counting provides valuable information for the diagnosis and treatment of a variety of conditions. Chamber cell count and cellularity analysis by optical microscopy are considered the gold-standard method for cell counting. However, this method has a long turnaround time and limited reproducibility, and requires highly-trained personnel. In the recent decades, specific modes have been developed for the analysis of body fluids. These modes, which perform automated cell counting, are incorporated into hemocytometers and urine analyzers. These innovations have been rapidly incorporated into routine laboratory practice. At present, a variety of analyzers are available that enable automated cell counting for body fluids. Nevertheless, these analyzers have some limitations and can only be operated by highly-qualified laboratory professionals. In this review, we provide an overview of the most relevant automated cell counters currently available for body fluids, the interpretation of the parameters measured by these analyzers, their main analytical features, and the role of optical microscopy as automated cell counters gain ground.