Hemato · Published 2026-06-22 · DOI 10.3390/hemato7020022
Georgios Boutsikas, Konstantinos Agiannitopoulos, Ioannis Anagnostopoulos, Myrofora Vikentiou, Maria Roumelioti, Athanasios Papatheodorou, Elisavet Kouvidi, Andriana Panoutsou, Georgios Georgiou, Aglaia Dimitrakopoulou, Nikolaos Paschalidis, Elisavet Economaki, Evdoxia Pouliou
Flow cytometry is an essential diagnostic method in hematology, and one of its main applications is the assessment of the clonality of mature B cells. We present a case report of a patient referred for the investigation of absolute lymphocytosis. The flow cytometry study revealed an increased percentage of B cells, but it could not establish B-cell clonality, based on the study of surface light chains in combination with the pattern of expression of mature B-cell markers. The diagnosis of Persistent Polyclonal B-cell Lymphocytosis (PPBL) was considered in the differential diagnosis as the mature B cells were found to be immunophenotypically memory B cells. However, due to the markedly elevated count of B cells, molecular testing with Polymerase Chain Reaction (PCR) for B-cell clonality based on IGH (Immunoglobulin Heavy Chain) gene rearrangements was performed, and it revealed the presence of two clones of B cells. Approximately one year later, the same work-up was repeated in the patient’s bone marrow aspirate. By flow cytometry, a distinct clonal B-cell population was isolated, while the molecular testing with PCR for B cell clonality based on IGH heavy-chain gene rearrangements revealed the presence of three clones of B cells. In addition, evaluation of the sample with high-dimensional mass cytometry showed the presence of four major immunophenotypically abnormal B-cell subsets.
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Boutsikas, G., Agiannitopoulos, K., Anagnostopoulos, I., et al. (2026). Flow Cytometry Immunophenotyping in Hematology Clinical Practice: Panacea or a Diagnostic Tool? Conclusions from a Case Report. Hemato. https://doi.org/10.3390/hemato7020022