A rare biclonal Hairy Cell Leukemia disclosed by an integrated diagnostic approach: A case report

Abstract

Hairy Cell Leukemia (HCL) is a rare indolent disease affecting mature B lymphocytes. While general symptoms are rather nonspecific (splenomegaly, fatigue, pancytopenia), HCL cells show a characteristic morphologic, immunophenotypic, and mutational profile that features prominently in the diagnostic process. Malignant cells have oval nuclei, abundant cytoplasm, and typical cytoplasmatic projections. Flow cytometric immunophenotyping includes key antigens such as CD11c, CD25, CD103, and CD200, which are strongly expressed, in addition to the ordinary panel used for the detection of B cell lymphoproliferative diseases (LPD). Moreover, a recurrent V600E BRAF mutation has been recently uncovered in HCL but not in its mimickers and is now considered the molecular hallmark of the disease (Cross & Dearden, 2020).Usually, LPD present one single clonal population, but bi-or

Hairy Cell Leukemia and HCL-Like Disorders: Diagnosis and TreatmentLeuc閙ie �Tricholeucocytes et Autres Prolif閞ations �Cellules Chevelues: Diagnostic et Traitement

“…Des phénotypes inhabituels ont été décrits: perte du CD123 [36] notamment en cas d'infection à SARS-Cov-2 associée, expression du CD5 [37] ou du CD10 [38]. De rares cas de LT biclonales ont été rapportés [39,40]. Pour distinguer la HCL de la HCL-V, la médiane d'intensité de fluorescence (MFI) du CD43, CD200 et du CD79b peut être utilisée: elle est plus élevée dans la HCL, mais celle du CD81 est plus basse comparée à celle observée dans la HCL-V [41].…”

Issue Highlights—November 2021

“…Vittoria et al describe a rare bi-clonal hairy cell leukemia (HCL) (Vittoria et al, 2021). In the initial flow cytometric evaluation, a subset of CD20 + B cells with high side scatter (SSC) comprising 15% of the total lymphocytes was observed.…”

“…The manuscript from Göçer and Kurto glu additionally highlights the impact of the cutoff values on the COU (Göçer & Kurto glu, 2021). Four Case Reports are also included in this issue (Smith et al, 2021;Sorigue et al, 2021;Tavarozzi et al, 2021;Vittoria et al, 2021). The general take home message from the case reports is the need to fully investigate anomalous findings.…”

Biclonality in hairy cell leukemia: Co‐occurrence of CD10+ and CD10− clones with different surface membrane immunoglobulin expression

“…Therefore, HCL cell immunophenotype resembles that of post-germinal center B lymphocytes, also based on immunoglobulin (Ig) gene rearrangements. Biclonality in non-Hodgkin lymphomas is infrequent accounting for less than 5% of total cases, and in HCL is an even rarer event, only anecdotally reported (Vittoria et al, 2021). We present a composite HCL case characterized by distinct expression of CD10 and SmIg.…”

“…Classical HCL cells are characterized by surface expression of CD19, CD20, CD22, CD11c, CD25, CD79b, CD103, CD123, FMC7, and monoclonal light chain immunoglobulin (SmIg) restriction. These cells are typically negative for CD5, CD10, and CD23; however, CD10 positivity has been reported in 5%-14% of all HCL cases and CD23 positivity in 17%-21% of patients (Maitre et al, 2022;Vittoria et al, 2021). Therefore, HCL cell immunophenotype resembles that of post-germinal center B lymphocytes, also based on immunoglobulin (Ig) gene rearrangements.…”