Background. As morphological pattern of bone marrow (BM) biopsy samples at advanced stages of clonal evolution in essential thrombocythemia (ET) appears similar to that in the development of post-thrombocythemic myelofibrosis and primary myelofibrosis (PMF), the expression of fibro-genesis factors by atypical megakaryocytes (MKC) acquires increased interest. Aim. To study the expression of the transforming growth factor TGFβF1 by atypical MKC; to relate the number of TGFβF1-positive MKCs with the degree of BM stroma fibrosis and trabecular bone changes in patients with ET and different PMF stages. Materials & Methods. BM biopsy samples of ET and PMF patients, obtained before cytoreductive therapy, were subjected to histochemical study with Gomori stain and Masson trichrome as well as to CD42b and TGFβF1 antibody immu-nohistochemical assays. The degree of myelofibrosis and osteosclerosis was estimated by semi-quantitative method in accordance with the European Consensus guidelines. The morphological characteristics of atypical MKC included the comparative evaluation of nuclear-cytoplasmic ratio. Results. The number of MKCs with high nuclear-cytoplasmic ratio was significantly higher in BM biopsy samples of patients with pre-fibrosis/early PMF (pre-PMF) stage and fibrosis stage of PMF (f-PMF) compared with BM biopsy samples of ET patients. The analysis of TGFβF1 expression showed different numbers of positive MKCs in the study groups. The matching of the number of TGFβF1-positive MKCs with the degree of myelofibrosis and osteosclerosis, with no regard to nosologic entities, revealed significant moderate correlation between these features (r = 0.431, p = 0.001 and r = 0.499, p = 0.001, respectively). In 55 % of pre-PMF patients’ BM biopsy samples, histochemical study with Masson trichrome stain visualized minimal immature osteoid deposits on bone trabeculae. Similar changes were also identified in f-PMF patients’ BM biopsy samples, whereas the ET patients’ samples featured none of them. Conclusion. The results of the study prove that the pathological clone of MKC with TGFβF1 expression affects myelofibrosis and osteosclerosis processes whose manifestation in BM biopsy samples is associated with the number of TGFβF1-expressing atypical MKCs.

Introduction . Primary myelofibrosis (PMF) is a clonal disease violating the cell composition, histological topography and stroma in bone marrow (BM). Allogeneic haematopoietic stem cell transplantation (allo-HSCT) is a curative therapy in PMF. Aim  — description of change in the haematopoietic tissue cell composition and stroma, as well as in trabecular bone in allo-HSCT patients with fibrotic PMF. Materials and methods . We studies 24 trephine biopsy samples from nine PMF patients with allo-HSCT at the intervals: I — 1 month prior to, II — past 1–3 months and III — past 4–6 months from allo-HSCT. BM trephine biopsy slides were prepared in a standard histological assay with haematoxylin—eosin and additional staining with Gomori’s silver and Masson’s trichrome. Morphological change was evaluated in reticulin and collagen stroma, bone trabeculae, cellularity and topography of haematopoietic tissue. Results . The BM trephine biopsies of interval I were morphologically distinguished in three types by haematopoietic cellularity, stromal and trabecular sclerotic change. Post-transplant intervals II and III (3–6 months after allo-HSCT) did not reveal these types but showed an evident myelofibrosis and osteosclerosis reduction and signs of a restoring bone remodelling cycle. Myelopoietic lineages recovered in stages: the erythroid germ restored in three, granulocytic — in six months, and megakaryocytic cellularity did not fully recover in six months. Myelopoietic cellularity recovery outpaced blood recovery, which may be due to induced myelodysplasia or disruption of stromal niches. Conclusion . Allo-HSCT leads to the disappearance of PMF-pathognomonic BM morphology reflecting a histological remission. The reduction of myelofibrosis and osteosclerosis and normalisation of the trabecular bone remodelling cycle in post-transplant periods indicates an impact of cell microenvironment on PMF pathogenesis and warrants research into the composition and histological topography of cell microenvironment in PMF.

AIM To estimate graft function after kidney transplantation during active herpesviruses or superinfection Materials and methods. The study included 32 patients (men 21, women 11) with end-stage chronic kidney disease. The median age was 43 years. Cytomegalovirus (CMV), EpsteinBarr virus (EBV) and human herpes virus 6 (HHV-6) DNAs were screened by RT-PCR in the donor's transplant biopsy, and recipients peripheral blood and urine after kidney transplantation (KT) on 0, 1, 2, 4, 6, 12 months. Antiviral antibodies (IgM and IgG) were also screened by Enzyme-linked immunoassay analysis (ELISA) along with PCR. The 500 or less copies of viral DNA per 105 nuclear cells or 1 ml of urine was considered as low, more than 1000 copies high. RESULTS On the first month after KT CMV DNA was detected in 50% of pts., EBV DNA in 40% and HHV-6 DNA in 33%. During first year after KT two or three viruses simultaneously were found in 12 recipients: CMV, EBV, and HHV-6 were detected in 5 recipients; CMV and EBV in 4 patients; CMV and HHV-6 in 2 pts; EBV and HHV-6 in 1 pt. Graft dysfunction was observed in 9 patients with a high concentration of viral DNA of one, two or three viruses simultaneously. An upraise of the concentration of virus DNA (CMV, EBV and HHV 6) was detected primarily in the urine, while in the blood its concentration was less than 500 cop or undetectable. Renal dysfunction was not observed on the background of low concentrations of viral DNA in urine and blood. However, with an increase of DNA concentration, an impaired graft function in 8 of 12 patients appeared. Low viral DNA level proved to be a background for another virus activation or bacterial/fungal superinfection. CONCLUSION Graft dysfunction occurs at high viral DNA levels detection during mono-or superinfection. Low viral load can serve as a background for another virus activation and/or bacterial/fungal superinfection.

Indications of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with primary myelofibrosis are intermediate-2 and high-risk group of DIPSS (Dynamic International Prognostic Scoring System), beginning of the disease in childhood. The other adverse factors affect engraftment and survival after allo-HSCT, example partialy matched donor. But the result of allo-HSCT from matched related donors and result of allo-HSCT from haploidentical donors are comparable. The method for haploidentical hematopoietic stem cell transplantation is T-cell-depletion. This is clinical case of T-cell-depleted haploidentical hematopoietic stem cell transplantation in patient with primary myelofibrosis, the diagnosis was established in childhood.

Introduction. The pathogenesis of the novel coronavirus infection COVID-19 is being actively studied. Nevertheless, our up-to-date knowledge of lymphoid tissue response in the secondary immune organs dur-ing severe COVID-19 remains extremely limited. The aim of the study was to evaluate patterns of immu-nomorphological alterations in lymph nodes in patients with severe COVID-19 and to assess lymphocytes functional activity in them. Materials and methods. Lymph node tissue (autopsy material) from 17 deceased patients with severe COVID-19 was examined by histological and immunohistochemical methods using antibodies to CD4, CD8, CD20, CD30, CD123, CD138, PD-1. Results. Examined lymph nodes demonstrated lymphoid follicles reduction and paracortex expansion with reactive plasmacytosis and extrafollicular B-cell activation as well as sinus histiocytosis, variable hemophago-cytic cells, and blood vessel congestion. Red thrombi were observed in some lymph nodes. Hemorrhages in the stroma were frequent, and massive hemorrhages were found in individual nodes. Immunohistochemical study revealed CD4+ T-helpers predominance in the paracortex andcytotoxic CD8+ lymphocytes depletion together with an increase in the expression of both the PD-1 suppressor protein and the CD30 activation anti-gen on the lymphocyte surface. CD123-positive plasmacytoid dendritic cells resided in sinuses in abundance. Conclusion. Demonstrated B-associated zone reduction and cytotoxic T-lymphocytes depletion with an up-regulation of PD-1 expression in the lymph nodes in patients with severe COVID-19 indicate immune response exhaustion. At the same time, observed significant reactive plasmacytosis with the presence of numerous T-helper cells constitutes a morphological substrate of the humoral immunity. These findings might indicate the ineffec-tiveness of the humoral response at late stages of COVID-19 infection in context of cytotoxic immunity failure. Keywords: novel coronavirus infection, SARS-CoV-2, COVID-19, B- and T- immune response, lymph node

Aim. To study the structure of Ph-negative myeloproliferative diseases (Ph- MPD) and to identify morphological markers for diagnosing masked polycythemia vera (PV). Materials & Methods. Bone marrow core biopsy samples from the database of pathology department of National Research Center for Hematology within the period from January 2014 to June 2017 provided the basis for analyzing the diagnosed Ph- MPD cases. The trial included the bone marrow core biopsy samples of the patients treated and fol-lowed-up not only at the National Research Center for Hematology but also at other medical centers in the Russian Federation in the context of clinical, laboratory and molecular data. Results. In 1611 Ph- MPD patients PV prevailed corresponding to 40.6 % of all cases. In the PV group the masked form was diagnosed in 29 % of patients. Primary myelofibrosis (PMF) was diagnosed in 26.6 % of all patients including 10 % of cases with pre-fibrosis/early stage. The 3d most frequent disorder was essential thrombocythemia (ET) which corresponded to 16 %. JAK2 driver mutation was identified in all 654 PV patients. In 4 cases out of them exon 12 mutation was detected. A similar mutation was found out in PMF (53 %) and ET (60 %). In 36 % of PMF patients and 27 % of ET patients CALR mutation was detected. MPL mutation was identified in 4 % of PMF cases and was not discovered in ET. Triple negative patients were identified in 7 % of PMF and 13 % of ET cases. The designation of “myeloproliferative disease unclassifiable” can be applied to 16.8 % of cases. The trial deals with morphological criteria for diagnosing masked PV during examination of bone marrow core biopsy samples. In 30 % of patients with masked PV (according to the 2017 WHO classification) and splenomegaly (> 14 cm) portal vein thrombosis was identified. Conclusion. In the Ph- MPD group PV diagnosis prevailed (40.6 %). The histological analysis of bone marrow core biopsy samples of the patients with the masked PV accounting for 29 % of all PV cases, revealed morphological features typical of overt PV. Histological analysis of bone marrow is a reliable method for diagnosing overt and masked PV. Among morphological characteristics of the bone marrow of patients with masked PV and portal vein thrombosis special attention should be paid to the MF-1 grade of reticulin fibrosis (29 % of cases) and loose clusters of megakaryocytes (71.4 %).

Mediastinal gray-zone lymphoma (MGZL, lymphoma with features intermediate between classical Hodgkin lymphoma and diffuse large B-cell lymphoma) was declared as a separate entity in WHO classification of Tumors of Haematopoetic and Lymphoid Tissues in 2008 and 2017 years. Despite of similar pathomorphological characteristics between primary mediastinal B-cell lymphoma and Hodgkin lymphoma, clinical features and optimal therapeutic approach to MGZL are not clearly defined. Usually MGZL manifests with mediastinal lymphadenopathy, although extranodal lesions often occur (grey-zone lymphoma, GZL). Patients with MGZL have unfavorable prognosis, taking into account high rate of relapse. This article describes two cases of MGZL. First case manifested by arrhythmias due to primary heart involvement. In spite of cardiac failure antracycline-containing chemotherapy (6 courses of R-DA-EPOCH) it allowed to achieve a complete remission and resolving of arrhythmias. Second case was represented by metachronous tumors: primary mediastinal B-cell lymphoma at the time of disease onset and classical Hodgkin lymphoma, NS II, diagnosed after disease progression. Thus, we demonstrated two examples of MGZL that differ by clinical manifestation, response to chemotherapy, which emphasizes an importance of pathogenesis studying, and using of new therapeutic approaches.

The paper focuses on Epstein-Barr virus (EBV)-associated inflammatory pseudotumor in the spleen, an extremely rare disease which so far remained undefined in the Russian literature. The morphology of it is not characterized by any specific features and is represented by a spindle-cell component with pronounced inflammatory infiltration which complicates differential diagnosis. Previously this nosology was regarded within a group of the so-called inflammatory pseudotumors due to the similarity of the clinical course and radiological presentation with tumor processes. Today the term “inflammatory pseudotumor” is considered obsolete, since as pathogenesis was being studied within this disease group, the individual forms with similar morphology and different histogenesis were identified. Differential diagnosis in the context of additional diagnostic techniques is based in such cases on a wide range of reactive states, benign and malignant tumors.