Detection of malignant cells in serous body fluids by counting high-fluorescent cells on the Sysmex XN-2000 hematology analyzer

Abstract

Introduction: The body fluid mode of the Sysmex XN-2000 hematology analyzer differentiates cells into mononuclear and polymorphonuclear white blood cells (WBC) and high-fluorescent cells (HFC). The aim of this study was to evaluate the performance of the HFC count for detecting malignant cells in serous body fluids.

Methods: Two-hundred and thirty serous fluids were analyzed on the Sysmex XN body fluid mode. HFC were measured as relative count (HFC/100 WBC) and absolute count (HFC/μL). All samples were microscopically screened on cytospin slides for the presence of malignant cells.

Results: Malignant cells were found by microscopic examination in 49 of 230 samples (21.3%). Malignant samples contained significantly higher percentages (10.2 vs. 2.6/100 WBC) and absolute numbers (65 vs. 10/μL) of HFC than nonmalignant samples (P < 0.001). Areas under the ROC curve for relative and absolute HFC count were 0.69 and 0.77, respectively. A cutoff level of ≥17 HFC/μL showed the best performance to predict malignancy, with 88% sensitivity and 61% specificity.

Conclusion: As serous body fluids will be more analyzed on automated analyzers in the future, HFC count can be a useful tool to select samples for microscopic review. Microscopic evaluation should be performed if HFC values are above a certain threshold (e.g. ≥17 HFC/μL) or in case of clinical suspicion of malignancy.

Keywords: High-fluorescent cells; Sysmex XN; body fluid mode; malignant cells; serous body fluids.