Telomere length shortening has been associated with genomic instability and acquisition of molecular lesions, but these processes have not been systematically studied across large cohorts of myeloid neoplasia (MN). As proof of concept for a novel, cross-validated whole-genome sequencing-based method of telomere content (TC) determination combined with mutations, transcriptomics, and functional assays, we studied TC in correlation with specific molecular features of a large cohort (N = 1804) of patients with MN, including acute myeloid leukemia (AML) and myelodysplastic syndrome. When compared with healthy participants and patients with nonclonal diseases such as persistent polyclonal B-cell lymphocytosis, both MN and nonmalignant controls with clonal disease, such as paroxysmal nocturnal hemoglobinuria and aplastic anemia, exhibited decreased TC. Furthermore, we show that TC is lowered in adult MN abrogating correlation with age with considerable TC diversification among certain morphologic and molecular subtypes. For instance, AML harbored the lowest TC. Furthermore, MN originating from a more mature cell of origin (eg, acute promyelocytic leukemia) or characterized by hyperproliferative driver mutations (eg, RAS pathway genes) had lower TC, possibly indicating a loss of telomere maintenance capacity. In contrast, compared with other mutations, MN subtypes arising in a context of profound genetic alterations, such as TP53 mutations and complex karyotype, exhibited a relatively higher/preserved TC. This phenomenon did not involve alternative lengthening processes but was rather consistent with an increased TC due to preserved activity of the telomerase complex. Our results describe a common and genotype-specific telomeric makeup of a large cohort of patients with MN providing a molecular benchmark for future therapeutic targeting of the telomere machinery.

Polyclonal B-cell lymphocytosis of English Bulldogs (PBLEB) is a lymphoproliferative disorder associated with splenomegaly and hyperglobulinaemia. Information regarding both the degree of expected lymphocytic organ infiltration and possible treatment protocols is limited, and clinical overlap with neoplastic lymphoproliferative disease presents a diagnostic challenge. Here, we report and discuss the case of a 5-year-old English Bulldog with PBLEB, presenting with a marked gammopathy, marked splenomegaly and subsequent abdominal distension resulting in gastrointestinal clinical signs. We present extensive clinicopathological and histopathological data, demonstrate marked infiltration of tissues including the bone marrow, and document a favourable clinical outcome following splenectomy.

Clonal mature B-cell lymphoproliferative disorders (B-LPDs) are a heterogeneous group of neoplasia characterized by the proliferation of mature B lymphocytes in the peripheral blood, bone marrow and/or lymphoid tissues. B-LPDs classification into different subtypes and their diagnosis is based on a multiparametric approach. However, accurate diagnosis may be challenging, especially in cases of ambiguous interpretation. Multiparameter flow cytometry (MFC) represents an extensively used technique to detect the presence of different cellular lines in immunology and hematology. MFC results provide an essential contribution to the B-LPDs diagnostic process, even more so considering that panels are constantly integrating novel markers to improve diagnostic accuracy. The aim was to evaluate the contributing role of MFC routinary studies by analyzing the expression and the mean fluorescence intensity (MFI) of CD200, ROR1, and CD43 in various B-LPDs to evaluate their usefulness in the differential diagnosis of these diseases. We retrospectively evaluated 2615 consecutive cases of newly collected samples (mostly from patients with lymphocytosis) analyzed by MFC carried out in the B-LPD diagnostic process referred to the Division of Hematology of the Sapienza University of Rome. We compared the results of CD200, ROR1, and CD43 expression percentage and their MFI between different subtypes of B-LPDs. In chronic lymphocytic leukemia (CLL), CD200, ROR1, and CD43 were always expressed with bright intensity. CLL samples presented high CD200 expression and MFI [CD200%, mean: 100 (range, 24-100); positivity rate: 100%; MFI, median = 125 (range, 10-1200)] statistically higher than mantle cell lymphoma (MCL) (p<0.001), which is usually negative for CD200, and variant hairy cell leukemia (vHCL, according to 2022 ICC) (p<0.001), but comparable with classic HCL (cHCL) (p>0.9). ROR1 resulted expressed in all CLL [ROR1%, mean: 100 (range, 52-100), positivity rate: 100%; MFI, median=50 (range, 10-202)] and MCL cases with comparable MFI (p>0.9). CD43 expression and MFI were significantly higher in CLL [CD43%, mean 99 (range, 59-100); positivity rate: 100%; MFI, median = 130 (range, 41-980)] than in MCL, vHCL, cHCL, and all the others mature B-cell neoplasia (p<0.001). CD200 and CD43 expression and MFI were significantly higher in cHCL compared to vHCL. Among the other mature B-cell neoplasia, CD200 was variably expressed in follicular lymphoma (FL), marginal zone lymphoma (MZL), diffuse large B-cell lymphoma (DLBCL), and lymphoplasmacytic lymphoma (LPL). ROR1 and CD43 presented a very low expression percentage in this latter group, being mostly negative. Persistent polyclonal B-cell lymphocytosis (PPBL) resulted in uniformly positive for CD200 and negative for ROR1 and CD43. Our data suggest that evaluating CD200, ROR1, and CD43 antigens and their intensity of expression, along with commonly used markers in MFC routine panels for B-LPDs, might be extremely useful for prompt diagnostic evaluation in the differential diagnosis of these diseases.

Persistent polyclonal B-cell lymphocytosis is a rare disease with chronic lymphocytosis of polyclonal origin, which is more frequent in mostly asymptomatic middle-aged female smokers. The hallmark of this entity is the presence of bilobed/binucleated B lymphocytes, which are polyclonal as demonstrated by immunophenotyping; an elevated IgM level is common. This disease shows, in most cases, an indolent course over many years and, although controversial, it may rarely convert to malignant lymphoma. In addition to smoking, a genetic predisposition for persistent polyclonal B-cell lymphocytosis is likely. Recurrent genetic aberrations have been described. The differential diagnosis includes non-Hodgkin's lymphoma and a clear distinction between both entities is of the utmost importance because treatment is generally not indicated in the former: instead, regular follow-up is recommended. The authors describe the case of a 46-year-old female smoker, who presented with chronic lymphocytosis, elevated IgM and circulating binucleated lymphocytes. Excluding lymphoma was important considering the unusual presentation with constitutional symptoms and splenomegaly. A linfocitose policlonal persistente de células B é uma doença rara, caracterizada por linfocitose crónica policlonal, que ocorre mais frequentemente em mulheres fumadoras de meia-idade, que se apresentam assintomáticas ou com sintomas inespecíficos. A presença de linfócitos B binucleados é considerada a assinatura citomorfológica desta entidade. A imunofenotipagem comprova a sua origem policlonal, observando-se muitas vezes uma elevação da IgM sérica. É controverso se existe um risco aumentado de desenvolvimento de linfoma. A predisposição genética é também um fator de risco, além do tabagismo. Apesar da sua natureza policlonal, alterações genéticas recorrentes estão descritas. Na linfocitose policlonal persistente de células B a abordagem terapêutica consiste habitualmente numa vigilância regular, o que reforça a importância do seu reconhecimento. Os autores descrevem o caso de uma mulher de 46 anos, fumadora, com linfocitose crónica, IgM elevada e linfócitos binucleados. O diagnóstico diferencial com linfoma assumiu particular importância, considerando os sintomas constitucionais e esplenomegalia que apresentava.

Persistent polyclonal B-cell lymphocytosis is a rare nonmalignant disorder characterized by mild persistent lymphocyte proliferation with possible evolution to aggressive lymphoma. Its biology is not well known, but it is characterized by a specific immunophenotype with rearrangement of the BCL-2/IGH gene, whereas amplification of the BCL-6 gene has rarely been reported. Given the paucity of reports, it has been hypothesized that this disorder is associated with poor pregnancy outcomes. To our knowledge, only two successful pregnancies have been described in women with this condition. We report the third successful pregnancy in a patient with PPBL and the first with amplification of the BCL-6 gene. PPBL is still a poorly understood clinical condition with insufficient data to demonstrate an adverse effect on pregnancy. The role of BCL-6 dysregulation in the pathogenesis of PPBL and its prognostic significance are still unknown. Evolution into aggressive clonal lymphoproliferative disorders is possible and prolonged hematologic follow-up is warranted in patients with this rare clinical disorder.