Introduction. The identification of mutations in the FLT3 gene is essential for the diagnosis, prognosis, and selection of treatment strategies for acute myeloid leukemia (AML).

Aim: to compare the main methods used in the diagnosis of FLT3 mutations in patients with AML.

Materials and methods. Identification of FLT3 gene mutations was carried out using polymerase chain reaction (PCR) with fragment analysis (PCR-FA), double-label PCR-FA, tandem duplication method (TD-PCR), next-generation sequencing (NGS), and allele-specific PCR (AS-PCR) in patients who were diagnosed or observed with AML at the National Medical Research Center for Hematology from 2017 to 01.06.2024.

Results. The PCR-FA method showed reliable results in the testing of internal tandem duplications of FLT3 gene (FLT3-ITD). The double-label PCR-FA method had greater sensitivity and specificity that allowed detection of FLT3-ITD in a larger number of patients. TD-PCR was useful for determining minimal residual disease (MRD) in some patients. NGS provided information about the site of ITD insertion and its nucleotide composition, but also expanded our understanding of point mutations in the first and second tyrosine kinase (TKD1 and TKD2) domains, which may cause resistance to tyrosine kinase inhibitors.

Conclusion. The use of several methods to analyze FLT3 mutations makes it possible to make a more accurate identification of minor FLT3-ITD clones, as well as the detection of MRD and somatic point mutations within the TKD1 and TKD2 domains. Recommendations are given on the molecular genetic diagnosis of FLT3 mutations in AML.

Introduction. TP53 gene mutations and cytogenetic abnormalities (MYC/8q24, BCL2/18q21, BCL6/3q27, del17p13, and complex karyotype) play an important role in prognosis and therapy selection for various lymphoproliferative diseases. However, their signifi cance in the pathogenesis and prognosis of primary mediastinal B-cell large cell lymphoma (PMBCL) remains poorly understood and warrants further investigation.

Aim: to assess the frequency of TP53 gene mutations and cytogenetic aberrations (MYC/8q24, BCL2/18q21, BCL6/3q27, del17p13, and complex karyotype) and their impact on treatment outcomes in PMBCL.

Materials and methods. The study included 51 patients who underwent therapy using the response-adapted DA-EPOCHR protocol from 2012 to 2024. Analysis of TP53 mutations (exons 4–10) was performed using high-throughput sequencing (n = 31/51 (61 %)). FISH analysis was conducted to identify chromosomal abnormalities involving the loci of MYC/8q24, BCL2/18q21, BCL6/3q27, and del17p13 (n = 31/51 (61 %)), and standard karyotyping was carried out (n = 31/51 (61 %)). Due to the low mitotic activity of tumor cells, suffi cient mitoses were obtained in only 16/31 (52%) PMBCL samples.

Results. TP53 mutations were identifi ed in 4/31 (13%) patients, with three of these mutations classifi ed as pathogenic. Isolated translocations involving MYC/8q24 and BCL6/3q27 loci were detected in 2/31 (6 %) patients. Structural rearrangements of chromosome 17 in the TP53 locus and translocations involving the BCL2/18q21 locus were not identifi ed in any case. At 36 months, overall survival in the TP53-WT and TP53-MUT groups was 85 % and 100 %, respectively (p = 0.61). The relapse/progression rate was 33 % in TP53-MUT patients and 20 % in TP53-WT patients (p = 0.35).

Conclusion. The fi ndings demonstrate the rarity and lack of prognostic signifi cance of the investigated markers in PMBCL patients. These results underscore the need for further research to identify driver events in biologically discrete subtypes of aggressive B-cell lymphomas, as well as risk factors specifi c to each subtype. Such research will provide a foundation for the development of precision therapy approaches.

Introduction. Human herpesvirus 6 (HHV-6) is an opportunistic agent causing various complications in patients with hematological diseases. The virus has a unique ability to integrate into telomeres of human chromosomes, which makes hereditary transmission of the viral genome possible. This form of the virus is called inherited chromosomally integrated HHV-6 (iciHHV-6). The iciHHV-6 frequency among patients with blood system diseases is unknown and its signifi cance for clinical practice remains insufficiently studied.

Aim — to determine the prevalence of ichHHV-6 in patients with hematological diseases.

Materials and methods. Clinical and laboratory data in 4,998 adult patients treated at the National Medical Research Center for Hematology (Moscow, Russia) from 2020 to 2024 were analyzed. Clinical materials obtained from patients were examined by molecular-biological methods for the presence of HHV-6 DNA.

Results. IciHHV-6 was confirmed in 14 out of 4,998 (0.26 %) enrolled patients. 5 patients (38,5 %) had clinical manifestations of herpesvirus infection during treatment, while the other 9 patients (61.5 %) showed no signs of the infection. 5 of 14 iciHHV-6-positive patients underwent hematopoietic stem cell transplantation. Criteria and laboratory tests for suspicion for iciHHV-6 were designed and successfully verified, which made it possible to suspect and prove the presence of hci-HCV-6.

Conclusion. The presence of ichHHV-6 among patients with hematological diseases was detected in 0.26 % of cases. The high concentration of HCV-6 DNA during polymerase chain reaction testing, as well as the absence of negative virological results during antiviral therapy, make it possible to suspect HCV-HCV-6. Screening for iciHHV-6 by qPCR of hair follicles and nails is recommended for patient with high viremia. A positive result in such tests confirms iciHHV-6-positive status. The efficiency of antiviral therapy in iciHHV-6-individuals requires further research. During transplantation of allogeneic hematopoietic stem cells to a recipient-carrier of hci-HCV-6, HCV-6 reactivation, asymptomatic persistence of high viremia, and a dramatic decrease of the viral load are all possible.

Introduction. Pathogen reduction technologies in donor blood products have provided a preventive approach against a variety of hemotransmissive infections as well as prevention of donor leukocyte complications. However, while pathogen reduction in plasma and platelet concentrates is currently widespread, methods for reducing pathogens in red blood cell (RBC)-containing products are still being studied.

Aim: to analyze the transfusion results of a pathogen-reduced RBC suspension in patients with various oncological and hematological diseases as well as defects of the immune system in order to prevent transfusion transmission of cytomegalovirus infection.

Patients and methods. The results of transfusion therapy of a pathogen-reduced RBC suspension for the prevention of transfusion transmission of CMV infection in 27 patients who underwent transfusions during a long follow-up period are presented.

Results. A total of 27 patients received 167 transfusions of pathogen-reduced RBC suspension. Transfusion efficacy, assessed by hemoglobin increase, was dependent on the transfusion volume per body weight, but was independent of the storage time of the RBC suspension over the measured interval. The transfusions were effective and tolerated without complications.

Conclusion. The clinical use of pathogen-reduced RBC suspension is safe and provides sufficient clinical and laboratory efficacy.

Introduction. Dried plasma has been used for more than 80 years. During this time the attitude to it has changed — from wide acceptance during the Second World War, to a complete ban in the post-war period and the resumption of production in recent years.

Aim: to analyze literature data on the production, safety, quality, storage and clinical efficacy of dried plasma.

Main findings. A history of the use of dried plasma is provided; the composition of dry plasma is analyzed depending on the production method, rehydration, storage duration and pathogen reduction. Information is provided on the clinical use and effectiveness of dry plasma, including concentrated dried plasma.

Introduction. Hepatitis E virus (HEV) is transmitted primarily through contaminated water and food, but cases of transfusiontransmitted HEV infection (TT-HEV) have also been described. TT-HEV may pose a serious risk for immunosuppressed patients, such as recipients of hematopoietic stem cell transplants or solid organ transplants. The risk of TT-HEV is associated with HEV viremia in asymptomatic donors. In recent years, several European countries and Japan have introduced universal screening of blood donors for HEV RNA.

Aim: to systematize published data on the prevalence of HEV infection among donors and the levels of risk of TT-HEV in different regions of the world, as well as approaches to screening donors for HEV.

Main findings. An analysis of the research data obtained in limited donor cohorts, as well as real-world data obtained following the implementation of universal donor screening indicates the relevance of testing blood donors for HEV RNA. The results of studies conducted in the Russian Federation indicate the frequency of detection of HEV viremia in donors comparable to that observed in countries where universal screening of donors for HEV RNA has already been implemented. The absence of documented cases of TT-HEV in the Russian Federation may be due not to the absence of the problem as such, but to insuffi cient availability of hepatitis E diagnostics and/or the lack of awareness of clinicians regarding this infection.

Introduction. Over the past decades, a number of classifications and their updates have been developed for acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). Myeloid neoplasms (MN) after previous therapy for other diseases had different designations. The fifth edition of the WHO classification provides the most accurate definition of these neoplasmes — MN post cytotoxic therapy (MN-pCT). The problem of choosing therapy for these MN is largely related to previous treatment of the first oncological disease.

Aim: to present the difficulties of classifying MN induced by previous cytotoxic chemotherapy of a hematologic malignancy and a solid tumor, as well as the difficulties of determining the prognosis and choosing a treatment method.

Main findings. Clinical cases of MDS after chemotherapy of AML and AML after anticancer treatment of osteosarcoma are described. The anamnesis, diagnostics procedures are reported in detail, and the choice of therapy is justified. Risk stratification of patients with MN associated with previous cytotoxic therapy is discussed.

Introduction. Immunophenotyping is a key diagnostic method for chronic lymphocytic leukemia (CLL), the most common lymphoproliferative disorder (LPD) in middle-aged and elderly individuals. Given the high prevalence of CLL, there is a need to standardize approaches to its immunophenotypic diagnosis, including the development of standardized panels of monoclonal antibodies, recommendations for sample preparation, and the formulation of reports to improve diagnostic accuracy.

Aim: to develop a unified laboratory report form and a standardized approach to using the necessary and sufficient combination of labeled monoclonal antibodies for the diagnosis of CLL.

Main findings. An All-Russian working group was formed under the National Hematological Society (NHS) to discuss key issues in the laboratory diagnosis of CLL. The primary focus was on problems related to immunophenotyping. Consensus decisions were made regarding the creation of a unified laboratory report form and a standardized approach to using the necessary and sufficient combination of labeled monoclonal antibodies for the diagnosis of CLL. The monoclonal antibody panel should include antibodies detecting CD19, CD20, CD5, CD23, and surface immunoglobulin light chains (k and λ). To differentiate CLL from other B-LPDs, additional markers such as CD43, CD200, CD10, CD22, and CD38 are recommended. The report form should include, along with patient information and sample type, the following: a list of used monoclonal antibodies, the flow cytometer model, the count of leukocytes and lymphocytes, the immunophenotype of the identified tumor population with emphasis on aberrant markers, the absolute count of pathological clone cells, and the final immunophenotypic variant of CLL or B-LPD.

Introduction. Thrombotic thrombocytopenic purpura (TTP) is a rare disease manifested by non-immune thrombocytopenia, microangiopathic hemolytic anemia and organ and system dysfunction.

Aim: to present the scheme of treatment of a patient with TTP.

Main findings. The case report of a 32-years-old patient, in whom TTP manifested with anemia, thrombocytopenia, and ischemic stroke, is presented. The patient was successfully treated with plasma exchange, prednisolone, caplacizumab, rituximab. Diagnostic errors, logic of prescription and cancellation of these or those drugs are discussed.