[IgD expression in various immunoarchitectural patterns of nodular lymphocyte predominant Hodgkin lymphoma in children]. / Ekspressiya IgD pri razlichnykh immunoarkhitekturnykh patternakh nodulyarnoi limfomy Khodzhkina s limfotsitarnym preobladaniem u detei.

BACKGROUND: Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) consist of lymphocyte predominant cell or LP-cell. Despite their origin from active germinal centers, in some cases LP-cells express IgD, which is characteristic of naive B-lymphocytes of the mantle zone. Due to the rarity of NLPHL, assessing the frequency of IgD-positive cases is difficult. This marker can serve not only for differential diagnosis with other diseases, but also indicate the possible heterogeneity of NLPHL, which is currently represented by six immunoarchitectural patterns. OBJECTIVE: To determine the frequency of IgD-positive cases of NLPHL in children with subsequent assessment of the association with types of immunoarchitectural patterns. MATERIAL AND METHODS: The study included 52 cases of NLPHL, which were divided to typical and atypical patterns. Differences between two groups were compared using Fisher's exact tests. RESULTS: IgD expression was found in LP-cells in 26 of 52 cases (50%) and was positively correlated with atypical types (typical - 5/23, 21.7% vs atypical - 21/29, 72.4%, p=0.0003), among which pattern C was most common. CONCLUSION: Due to the high incidence of IgD-positive cases in NLPHL, this marker may be useful in differential diagnosis with histologic mimics. At the same time, positive IgD status was associated with atypical patterns, which may likely determine the different biology of neoplastic cells within the same form.

[Clinical and morphological characteristics of Ewing's sarcoma and the algorithm for diagnosing undifferentiated round cell sarcomas]. / Kliniko-morfologicheskaya kharakteristika sarkomy Yuinga i algoritm diagnostiki nedifferentsirovannykh kruglokletochnykh sarkom.

BACKGROUND: The group of undifferentiated round cell sarcomas, according to the World Health Organization Classification, in addition to Ewing's sarcoma (ES), includes round cell sarcoma with rearrangement of the EWSR1 gene with partners not from the ETS gene family, sarcoma with BCOR gene alterations, CIC -rearranged sarcoma. Despite the fact that all tumors have clear histological and immunological criteria, their diagnosis can be difficult, given the fact that there are overlapping variants of the morphological picture and immunophenotype both within the group and with other round cell tumors. OBJECTIVE: Present a comparative analysis of genetically verified ES, sarcoma with BCOR gene alterations and CIC-rearranged sarcoma. MATERIAL AND METHODS: A comparative study of biopsy specimens of bones, soft tissues and internal organs was carried out in 118 patients with ES, 10 with BCOR gene alterations and 8 with CIC-rearranged sarcomas. All cases were genetically verified. The following research methods were used: histological, immunohistochemical, RT-PCR, RNA sequencing and FISH. RESULTS: Within our cohort, it was shown that ES predominantly affects bones, while soft tissue localization is more typical for the other two undifferentiated round cell sarcomas. Histologically, in the overwhelming majority of cases, ES is characterized by a monomorphic round-cell structure; on the contrary, heterogeneous structure is typical for sarcoma with alterations of the BCOR gene, CIC-rearranged sarcoma. High sensitivity and specificity of CD99/NKX2.2 co-expression for ES, BCOR/SATB2/TLE1 for sarcoma with BCOR gene alterations, high specificity and low sensitivity of WT1/ETV4 co-expression for CIC-rearranged sarcoma was shown. CONCLUSION: For the differential diagnosis of undifferentiated round-cell sarcomas, it is necessary to take into account the clinical, morphology when compared with the data of the IHC study, and verification by molecular genetic methods is necessary to improve the accuracy of diagnosis.

[«Malignant stroma?¼ Alternative localization of classical genetic aberrations in neuroblastoma]. / Zlokachestvennaya stroma? Al'ternativnaya lokalizatsiya klassicheskikh geneticheskikh aberratsii v neiroblastome.

Neuroblastoma (NB) is a malignant neoplasm originating from the primary cells of the sympathetic nervous system. Patients with NB are risk-stratified using a number of features including age at diagnosis, disease stage, tumor histology and genetic profile (status of NMYC, ALK genes, regions 1p and 11q). The interpretation of the results of genetic studies can become a source of problems because neuroblastoma has a heterogeneous histological pattern. The article describes 2 cases with classical for NB chromosomal aberrations in the stromal component of the tumor.

[CIC-rearranged sarcoma: a case report and literature review]. / CIC-perestroennaya sarkoma: klinicheskoe nablyudenie i obzor literatury.

CIC-rearranged sarcoma is a rare and extremely aggressive tumor that occurs mainly in soft tissues. Despite the fact that identification of a characteristic genetic rearrangement is necessary to verify the diagnosis, in most cases, the correct diagnosis can be made by comparing histological signs and a characteristic immunophenotype, which greatly speeds up the diagnosis. The article describes a case of CIC-rearranged sarcoma in a 14-year girl with the successful application of the CWS-2009 treatment protocol.

[Alveolar rhabdomyosarcoma: novel surrogate markers associated with oncogenic translocation]. / Al'veolyarnaya rabdomiosarkoma: novye vspomogatel'nye surrogatnye markery onkogennykh translokatsii.

BACKGROUND: Anomalies of the FOXO1 gene in alveolar rhabdomyosarcoma are associated with a worse clinical prognosis, which determines the high value of studying the status of this gene when choosing a therapy strategy. The «gold standard¼ for determining FOXO1 gene rearrangements is currently the fluorescent in situ hybridization (FISH) technique. OBJECTIVE: Study of the relationship between canonical FOXO1 translocation and immunohistochemical expression of new surrogate markers in alveolar rhabdomyosarcoma to determine their predictive value. MATERIAL AND METHODS: 139 cases of rhabdomyosarcoma were retrospectively studied. The study used tissue matrix technology (TMA). On sections obtained from TMA blocks, the FISH technique was implemented using the locus-specific probe MetaSystems XL FOXO1 Break Apart (Metasystems, Germany). Immunohistochemical studies were performed on similar sections from TMA blocks with OLIG2 (Cell Marque Antibodies, clone 211F1.1) and MUC4 (Cell Marque Antibodies, clone 8G7) antibodies. RESULTS: The final expression analysis and statistical processing using a 2x2 contingency table and Fisher's exact test passed 111 cases (76 without FOXO1 rearrangement and 35 with rearrangement). The specificity of OLIG2 and MUC4 expression for FOXO1-rearranged alveolar rhabdomyosarcoma was 85.53% and 80.26%, respectively (p<0.01). CONCLUSION: The present study confirms the high predictive value of the expression of surrogate markers OLIG2 and MUC4 in determining the genetic status of alveolar rhabdomyosarcoma, which makes it possible to predict with high specificity the detection of the FOXO1 gene rearrangement.

[Features of the cell composition of inflammatory infiltrate in different phases of diffuse alveolar lung damage with COVID-19]. / Osobennosti kletochnogo sostava vospalitel'nogo infil'trata v raznye fazy diffuznogo al'veolyarnogo povrezhdeniya legkikh pri COVID-19.

BACKGROUND: Acute respiratory distress syndrome (ARDS) with COVID-19 has a worse prognosis than ARDS with other diseases. Mortality from ARDS with COVID-19 is 26.0 - 61.5%, and due to other causes - 35.3-37.2%. OBJECTIVE: To find of the correlation between polymorphonuclear leukocytes (PMNs), lymphocytes, and macrophages in the cellular composition of the inflammatory infiltrate at different stages and phases of diffuse alveolar damage (DAD) with COVID-19, analyzing the autopsy material. MATERIAL AND METHODS: The lung tissue of 25 patients who died from ARDS with COVID-19 without a secondary bacterial or mycotic infection, another thanatologically significant pathology of the lungs, was studied. To study the cellular composition of the inflammatory infiltrate and the dynamics of its changes a double immunohistochemical analysis of the expression of antibodies to CD15, CD3, and CD68 was used. RESULTS: The inflammatory infiltrate and intraalveolar exudate in the exudative phase of DAD was represented by 56.8% of PMNs (CD15-positive cells; hereinafter - the average value of the percentage of positive cells to the total number of cells of the inflammatory infiltrate), 6.9% - lymphocytes (CD3-positive cells) and 19.5% macrophages (CD68-positive cells). In the early stage of the proliferative phase: 14.1% PMNs, 38.7% lymphocytes and 13.5% macrophages. In the late stage of the proliferative phase: 11.3% PMNs, 14.5% lymphocytes and 39.3% macrophages. CONCLUSIONS: In the exudative phase of DAD a statistically significant predominance of PMN was revealed, which could determine the main volume of lung damage and the severity of ARDS with COVID-19. In the early stage of the proliferative phase of DAD, a statistically significant change in the composition of the inflammatory infiltrate was revealed to compare with the exudative phase: a significant decrease in the content of PMNs relative to the total number of cells in the inflammatory infiltrate; an increase in the number of lymphocytes, which is probably associated with the start of organization and repair processes. In the late stage of the proliferative phase of DAD, compared with its early stage, was revealed a statistically significant increase in the number of macrophages in ratio.

[Angiomatoid fibrous histiocytoma: a literature review and a report of two cases]. / Angiomatoidnaya fibroznaya gistiotsitoma: obzor literatury i opisanie dvukh nablyudenii.

Angiomatoid fibrous histiocytoma (AFH) is a rare soft tissue tumor of intermediate malignancy potential, which predominantly affects children and young adults. This paper describes two cases of AFH, as well as a review of literature during 1979 to 2021. It gives data on the epidemiology, clinical features, diagnosis, and genetic characteristics of AFH.

[Rhabdomyosarcomas: structural distribution and analysis of an immunohistochemical profile]. / Rabdomiosarkomy: strukturnoe raspredelenie i analiz immunogistokhimicheskogo profilya.

Rhabdomyosarcoma (RMS) is a malignant soft tissue tumor originating from primitive mesenchymal cells, which is most common in children. OBJECTIVE: To qualitatively and quantitatively assess the expression of myogenic transcription factors on a large sample, to identify potential phenotypic differences, and to estimate the distribution and frequency of aberrant markers, such as ALK, PAX5, WT1, PCK, CAM5.2, SIX1, and Synaptophysin. MATERIAL AND METHODS: The investigation included 202 tumor tissue samples. Five tissue microarrays were assembled from the obtained material for subsequent histological and immunohistochemical studies. RESULTS: Embryonal RMS (ERMS) was diagnosed in 103 cases; alveolar RMS (ARMS) was detected in 80; spindle-cell/sclerosing RMS (SRMS) was found in 16 cases; epithelioid RMS (EpiRMS) was diagnosed in 2 patients. The expression of Myogenin and MyoD1 was detected in all the examined RMS tissue samples. ARMS was more characterized by staining at 1+ and 2+ intensities; at the same time, more than 50% of ERMS, SRMS, and EpiRMS cases showed staining at 1+ intensity. ALK expression was investigated using the D5F3 and p80 clones. The D5F3 clone displayed a higher staining intensity than the p80 clone (p<0.05). The expression of PAX5 was observed in 13 of 75 ARMS cases. That of WT1 and SIX1 was found in all RMS groups. CONCLUSION: The morphological diagnosis of RMS requires a careful assessment of all of the above factors, especially taking into account the variability in the expression of myogenic transcription factors and the high level of phenotypic aberration.

[Secretory carcinoma of the salivary gland (mammary analogue secretory carcinoma) in children]. / Sekretornaia kartsinoma sliunnykh zhelez (analog sekretornoi kartsinomy molochnoi zhelezy) u detei.

Secretory carcinoma of the salivary gland is a tumor that was first described less than 10 years ago and that mainly occurs in the parotid salivary gland in the elderly. Analyzing the literature over 8 years since the first description of the tumor identifies the main clinical, morphological, and genetic signs of the diagnosis of secretory carcinoma with a focus on the pediatric population. Four new cases of secretory carcinoma of the salivary glands, which have been diagnosed in children of the youngest age encountered in the literature, are also described.

[Extrarenal rhabdoid tumor: A review of literature and a report of cases with atypical morphology]. / Ékstrarenal'naia rabdoidnaia opukhol'. Obzor literatury i opisanie sluchaev s netipichnoi morfologiei.

Extrarenal extracranial rhabdoid tumor (EERT) is a rare malignant pediatric tumor characterized by extremely aggressive behavior, rapid metastatic spread, low survival rates, and no targeted therapy. The morphological diagnosis of classical cases of EERT is not difficult and it is based on its characteristic histologic pattern and immunohistochemical findings in a relatively short time, which allows one to immediately initiate therapy. The paper describes two cases of ERRT in the complete absence of classical rhabdoid morphology, as revealed by light microscopy when the material was primarily assessed. The final diagnostic search could establish a diagnosis of EERT in both cases on the basis of immunohistochemical findings.

[Non-ossifying fibroma (metaphyseal fibrous defect)].

Non-ossifying fibroma (NOF) or metaphyseal fibrous defect (MFD) is benign fibroblast proliferation with the presence of osteoclast-like multinucleated giant cells. The most cases of NOF/MFD occur in the metaphysis of the long tubular bones of the lower extremities, more commonly in the metaphysis of the femur and in the proximal metaphysis of the tibia. This lesion has a characteristic X-ray pattern and requires no surgical intervention, except for cases of a pathologic fracture or a risk for the latter. The paper analyzes 35 NOF/MFD cases in children and adolescents. It has been found that one and all patients have undergone surgery, suggesting the low awareness of this abnormality among radiodiagnosticians, pathologists, and surgeons.

[Osteochondroma in children and adolescents].

Osteochondroma is called a benign cartilage-forming tumor arising from an aberrant subperiosteal cartilage. Multiple osteochondromas syndrome (MOS) is an autosomal dominant disease, the basis for which is mutations in the EXT (EXT1 or EXT2) genes. Osteochondroma is one of the most common benign bone tumors. According to the WHO data, it is detectable in 35% of benign bone tumors and 8% of all surgically removed bone tumors. A total of 491 cases of bone tumors were analyzed in the children and adolescents diagnosed at the Department of Pathoanatomy, Russian Children's Clinical Hospital, Moscow, in 2009 to 2014. All the patients with osteochondroma were divided into 2 groups: 1) sporadic cases (n = 63) and 2) tumors included in MOS (n = 33). Both groups showed a preponderance of boys (39 boys and 24 girls in Group 1 and 21 boys and 12 girls in Group 2). Clinical, radiological, and morphological criteria for the diagnosis and differential diagnosis of osteochondromas in children and adolescents are given.

[Classical osteosarcoma in children and adolescent].

Classical osteosarcoma is one of the most common primary malignant bone tumors in children and adolescents. It more frequently occurs in the areas of the highest growth plate proliferation: limb long bones particularly in the distal femur (30%), proximal tibia (15%), and proximal humerus (15%). In the long bones, the tumor is located usually in the metaphysis (90%), less frequently in the diaphysis (9%), and very rarely in the epiphysis. This paper considers the clinical, radiological, and histological diagnosis, and prognosis in this pathology.

[Atypical teratoid/rhabdoid tumors of childhood].

The paper describes 6 cases of atypical teratoid/rhabdoid tumors (ATRT) in the complete absence of classical rhabdoid elements isolated from 25 INI1-negative central nervous system tumors investigated in the period 2006 to the present time. Analysis of the specific features of the histological structure of INI1-negative tumors could identify a few histological types of ATRT according to the conventionally standardized criteria for diagnostic search.

[Turcot syndrome. Rare observation and literature review].

The Turcot syndrome is a rare disease which is characterized by a combination of a brain tumor with a y at which the neoplasm of the colon. About 150 of such observations are described in world literature. Our own observation and a literature review are presented in this article.

[Sarcomatoid carcinoma of the thymus].

Sarcomatoid carcinomas are rare malignancies composed of epithelial (carcinomatous) and sarcomatous elements. High-grade carcinoma is difficult to diagnose by light optic and immunohistochemical studies. The authors give the data available in the literature on sarcomatoid carcinoma of the thymus and also describe their own observation. Its histological pattern is represented by a combination of carcinomatous and sarcomatous elements with extensive necrotic foci. Immunohistologically, the tumor cells expressed total cytokeratin (AE1/AE3), CD99, and focally epithelial membrane antigen. Some tumor cells were vimentin- and SMA-positive. Markers, such as chromogranin A, bcl-2, bcl-6, S-100 protein and myogenin, were negative.

[Transforming growth factor as a marker beta of nephrogenetic disturbance in congenital obstructive uropathies].

The paper presents the results of morphological and immunohistochemical studies of the kidneys and ureters obtained at surgery in 25 children aged from 2 days to 3 years who had congenital obstructive uropathies. The morphological study revealed varying renal tissue dysplasia concurrent with dysplasia of the prepelvic or distal ureter. Immunohistochemically, the kidneys showed a pronounced expression of TGFbeta1, TGF(1R1 and R2 in the nephrocytes of non-differentiated and collecting tubules, in the tubular lumen, vascular walls, in the interstitial tissue and cell interstitial infiltrates, on the hypoplastic and disoriented ureteral smooth muscle fibers. The use of the ILIAS-method to determine urinary TGF levels before and after surgery indicated a direct correlation of these indices with the degree of renal tissue dysplasia.

[Morphological and immunohistogenetical features of colon cancer in children].

We carried out postmortem and immunohistological studies of 3 cases of colon cancer in a 14-year-old (case 1) and an 8-year-old girl (case 2), and Turcot's syndrome in a 14-year-old girl (case 3). Tumors were located in the proximal portions of the colon and they were of rare histological types. The expression of proteins--the products of MLH 1, MHS2, and MHS6 genes responsible for DNA reparation was estimated. There was no expression of MLH1 and MHS6 in cases 2 and 3, respectively. The findings enabled the authors to assign these cases to hereditary polyposis-unassociated colonic cancer that is also a variety of Turcot's syndrome.

[Variants of formation of v. testicularts sinistra in children with varicocele].

Biopsies of veins of 20 boys with varicocele were studied morphologically. Three types of veins were observed. The first type was represented by veins with a wide lumen and the wall consisting of three layers of smooth muscle cells. The second morphological variant--veins of varying diameter of irregular shape and thin, frequently sclerosed wall. The third type were veins of a small diameter with well developed muscular layer. Immunohistochemical studies detected disturbances of vascular wall components suggesting the development of varicocele as a complex of congenital pathology with secondary alteration and destabilisation of compensatory processes.

[Morphological features of juvenile colon polyps in children]. / Morfologicheskie osobennosti iuvenil'nykh polipov tolstoi kishki u detei.

Histological, histochemical and immunohistochemical studies of 50 solitary juvenile polyps (JP) and 50 JP from children with juvenile polyposis syndrome (JPS) were performed. Observations of the focal complex glandular structures with high mitotic rate were more frequent in JP from patients with JPS (n = 29, 58%) than in solitary JP (n = 17, 34%) (p < 0.03). The immunohistochemical study demonstrated p53 overexpression in individual cells and more than 50% of Ki-67-positive cells in 5 (10%) solitary JP and in 17(34%) JP from patients with JPS (p < 0.007). The finding of microglandular pattern is more typical for JP from patients with JPS. Pathological data, expression of p53 and Ki-67 by immunohistochemistry could help to pick out the group of JP with dysplastic changes.