To determine the accuracy and reproducibility of morphological findings in the group of dysplastic nevi. A total of 178 skin resection specimens for 2023 were used in our study, which can be conditionally divided into three groups according to the correct clinical diagnosis: (1) with suspected dysplastic nevus/melanoma - 56% (99/178), (2) dysplastic nevus - 35% (62/178), (3) without dysplastic nevus/melanoma - 9% (7/178). Of the 178 observations, 31 cases were selected for further review. The selection criteria were the following morphological findings: (1) DN with moderate/severe atypia, (2) DN with any degree of atypia without clinical suspicion for it, (3) melanoma without clinical suspicion for it. Agreement between pathology reports and the original diagnosis was measured by the proportion of the same reports in the same educational category, using Wilson 95% confidence interval. There were 72 dysplastic nevi after first pathology report: 77.8% (56/72) with mild atypia, 18.1% (13/72) with moderate atypia, 4.2% (3/72) with severe atypia. The agreement between the clinical and primary morphological diagnoses was 58.4% (104/178), and in the dysplastic nevus group - 40.3% (25/62). When reviewing the 31 cases, the percentage of agreement for a simple nevus was 100%, for dysplastic with mild atypia - 70.8%, for dysplastic nevus with severe atypia - 33.3%, for melanoma - 48.4%. The coincidence of the initial and repeated diagnoses was 54.8% (14/31), 51.6% (16/31) and 29.0% (9/31) for each of the doctors. Our study revealed low accuracy and reproducibility of morphological conclusions in the group of dysplastic nevi. The determination of similar lesions by different pathologists and deviations from the initial diagnoses can primarily be explained by insufficiently reproducible diagnostic criteria.

To assess the state of the vascularization of the simple endometrial hyperplasia without atypia and to compare the obtained results with literary data. Vascularization of the endometrium in its simple hyperplasia without atypia was studied in 31 women by light microscopy using an immunohistochemical reaction with antibodies to the CD34 antigen and morphometry. Different patients had different degrees of expression, but always large, vascularization of the endometrium with simple endometrial hyperplasia without atypia. The vessels accounted 5.97±4.18% of the section area, while their number per 1 mm2 was 391±180. These data significantly exceed most of the results of other studies presented in the literature, which differ several times even from each other. Endometrium with simple endometrial hyperplasia without atypia is characterized by different, often very high levels of vascularization, the real average values much exceed most of the literary data, which are also very contradictory. A very critical attention to the results describing the features of angiogenesis and vascularization of hyperplastic endometrium without atypia is necessary.

Undifferentiated small round cell sarcoma of bone and soft tissue are rare, malignant neoplasms, often presenting diagnostic challenges due to its overlapping features with other conditions such as osteomyelitis and Brodie abscess. Accurate diagnosis requires a combination of imaging studies, histopathology, and genetic testing. Delayed or misdiagnosis can impact the prognosis and treatment outcomes. We present the case of a 34-year-old female who initially presented with persistent left upper thigh pain. Initial imaging raised suspicion of chronic osteomyelitis, with subsequent MRIs showing abnormal bone marrow edema and a lytic lesion in the left femoral diaphysis. Despite undergoing multiple biopsies, results remained inconclusive, with differential diagnoses including Brodie's abscess. The patient experienced temporary improvement, but her symptoms recurred, prompting further investigations. A repeat MRI showed the progression of intramedullary lesions and the appearance of new focal lesions. A biopsy eventually confirmed the presence of a malignant round cell tumor, identified as Ewing sarcoma through immunohistochemical evaluation and detection of EWSR1 gene rearrangement on FISH analysis and further NGS confirming EWSR1-NFATC2 fusion, diagnostic of the rare entity - round cell sarcoma with EWSR1-NFATC2 fusion. This case highlights the diagnostic complexities of round cell sarcoma of bone, which can mimic other benign bone lesions. It underscores the importance of multidisciplinary evaluation, genetic testing, and timely oncological intervention to improve patient outcomes.

Primary central nervous system lymphoma is a rare type of extranodal non-Hodgkin's lymphoma that occurs primarily in the central nervous system and represented by diffuse B-cell large cell lymphoma. Despite the fact that this tumor has been known for almost 100 years, studying it is difficult due to the rarity and, consequently, the limited number of statistically significant samples for research. This review analyzes the available literature data on the biological features of primary central nervous system lymphomas, pathogenesis and tumor microenvironment. In addition, we analyzed prognostic factors and current treatment strategies. The objective of this review is to determine the prospects for further study of this tumor.

Guillain-Barré syndrome is an acute immune-mediated polyradiculoneuropathy, which is the most common cause of acute paralysis and requires intensive therapy in one third of cases. Considering the fact that the disease is rare and characterized by low mortality, morphological changes in it are described rather modestly, based on isolated examples. The article analyzes literature data and our own observations of Guillain-Barré syndrome, including an analysis of clinical data, treatment, and the nature of structural changes based on routine, histochemical, and immunohistochemical studies.

The pathogenesis of diseases associated with amyloid deposition in various organs and tissues has been a concern for researchers and clinicians since their discovery. Particular attention is paid to the relationship between amyloidogenesis and neurotrophic disorders in age-related neurodegenerative pathology. In this context, the amyloid cascade theory and the neurotrophic dysfunction theory remain relevant, as evidenced by the results of numerous studies conducted in recent years. Meanwhile, it has been shown that amyloidosis, being a systemic pathological process, affects ocular tissues and extraocular structures in various forms with diverse clinical and morphological manifestations. This highlights the need for improved diagnostics of ocular amyloidosis and the study of its association with geriatric ophthalmic diseases such as age-related macular degeneration (AMD), senile cataract, primary open-angle glaucoma, and pseudoexfoliation syndrome. Accumulating evidence suggests that both amyloidogenesis and neurotrophic disturbances share common triggers and mutually contribute to the development of neurodegenerative pathology in both AMD and Alzheimer's disease (AD). Therapeutic strategies aimed not only at suppressing amyloidogenesis and correcting neurotrophic dysfunction but also at the overall regulation of these two pathogenic mechanisms may have a positive effect on geriatric ophthalmic diseases and AD, significantly improving the quality of life of elderly patients. This article summarizes current concepts on the role of neurotrophic dysfunction and amyloidogenic processes in the development of AMD.

To study the prognosis of poorly cohesive gastric carcinoma depending on the amount of the signet ring cells and depth of tumor invasion in comparison with other types of gastric cancer (GC) according to the classification of P. Lauren. In 315 patients with GC after surgical treatment, pathological tissue samples were reviewed by using a semi-quantitative assessment of the proportion of diffuse and intestinal components of the tumor to clarify the type of GC according to the P. Lauren classification, as well as the proportion of signet ring cells. In pT1-T2 tumors, 5-year overall survival (5-OS) in patients with diffuse and intestinal types of gastric cancer has demonstated no differences. In cases of serous membrane invasion (pT4a-T4b), the 5-OS rates in patients with poorly cohesive gastric carcinoma worsens sharply compared to the intestinal type (28.6% versus 49.7%, p=0.006) and becomes comparable with 5-OS in mixed type of gastric cancer (15.2%, p=0.644). As the depth of invasion increases, the amount of signet-ring cells in poorly cohesive cancer decreases. The highest percentage of signet ring cells was found when the tumor was localized within the mucous and submucous layers (27.5% for pT1a, 43.0% for pT1b). For pT2, the proportion of signet ring cells was 12.0%, for pT3 - 11.2%, pT4 - 8.3%. This feature explains the high percentage of early cancer in patients with signet ring cell (SRC) GC. No significant differences in 5-OV was found with poorly cohesive carcinoma depending on the amount of signet ring cells (≥1%, ≥10%, ≥50%, ≥90%). Invasion of the serous membrane of the stomach contributes to the rapid implementation of the tendency of poorly cohesive gastric carcinoma to peritoneal dissemination of the tumor. The proportion of signet ring cells in poorly cohesive gastric carcinoma does not affect to aggressive properties of the tumor.

Estimate the prevalence of the most clinically significant genetic events in different histological groups and among neuroblastomas in general and to demonstrate rarer genetic findings. A total of 233 cases of patients with neuroblastoma, for whom the histological conclusion and the results of cytogenetic examination by FISH (the status of the MYCN gene and chromosomal regions 1p and 11q) were known, were analyzed. Based on these data, the cases were divided into favorable and unfavorable histological groups, in each of which the presence of genetic abnormalities was analyzed. Also, 28 cases of patients with large cell neuroblastoma were analyzed, for whom the histological conclusion, MYCN gene status, immunohistochemical expression of MYC protein and the results of cytogenetic study of MYC gene status by FISH were known. MYCN gene amplification, 1p deletion/imbalance and 11q deletion/imbalance are more common in tumors from the unfavorable morphological group. Aberrations of the chromosomal region 1p and MYCN amplification are events that often occur together, while 11q aberrations, on the contrary, have an inverse correlation with MYCN amplification. 11q deletion/imbalance is more often detected in tumors with MYCN gain. In 4 cases, 1p and 11q chromosomal aberrations were detected in the same tumor, all in the unfavorable histological group. Two cases with chromosomal aberrations in stromal cells were also identified. Expression of MYC protein was detected in 5 cases, of which 2 showed amplification of the MYC gene.

Develop an AI-based model for detecting PCa in biopsy samples and compare its diagnostic performance with pathologists with varying levels of experience. A training dataset comprising 470 core biopsy specimens of prostate tissue from 86 patients was utilized. The AI model employed a U-Net neural network architecture. For testing, a separate dataset of 282 scanned specimens, not included in model training, was separated in 2 sets - 1 and 2 (with 141 slides in each). This dataset consisted of 81 specimens with non-neoplastic prostate tissue and 201 specimens with adenocarcinoma structures. The study included 20 pathologists with varying levels of experience from 12 medical institutions in the Russian Federation, who evaluated each case on the «PathVision.ai» platform. The diagnostic performance and agreement between the AI model and pathologists were assessed using comparative statistical analysis. The AI-model demonstrated high diagnostic performance, with sensitivity of 0.99 [95% CI: 0.97-1.00], specificity of 0.93 [95% CI: 0.84-0.97], and accuracy of 0.98 [95% CI: 0.95-0.99] for detecting PCa. These metrics surpassed those of junior pathologists (sensitivity: 0.92 [95% CI: 0.91-0.94]; specificity: 0.89 [95% CI: 0.86-0.91]; accuracy: 0.91 [95% CI: 0.90-0.93]) and were comparable to those of experienced pathologists (sensitivity: 0.93 [95% CI: 0.91-0.95]; specificity: 0.94 [95% CI: 0.91-0.96]; accuracy: 0.94 [95% CI: 0.92-0.95]). Developed model «PathVision.ai» in pilot study demonstrated high sensitivity, specificity and accuracy in the diagnosis of PCa in biopsy samples.

To evaluate neuroimaging, microscopic features and proliferative activity in meningioma recurrence and continued growth. Histological and immunohistochemical studies of tumor biopsies were performed in 16 patients with tumor progression who underwent surgery for recurrence and continued growth of intracranial meningiomas; the comparison group included 10 patients with newly diagnosed intracranial meningioma. All patients were performed pathomorphological and radiological examination assessment. The average tumor volume in the meningioma progression group was 48.88±14.32 cm3; the average tumor volume was higher in the primary surgical treatment group - 51.51±14.48 cm3. Recurrent tumors were characterized by more pronounced cellular and tissue atypia, patterns of infiltrative growth with the involvement of large vessels. The meningioma proliferative activity, assessed by Ki-67(max) expression, was higher in the group with meningioma progression and amounted to 9.71±2.5%. Significant differences in the Ki-67 expression were noted by tumor localization, grade, and brain invasion (p<0.05) in the meningioma recurrence and continued growth group. Recurrent meningiomas are represented by different grade tumors, including benign typical meningioma (grade 1), which indicates the need for greater attention and patient follow-up with this pathology. There are differences in terms of grade progression and locally destructive growth in meningioma recurrence and continued growth. This indicates a more pronounced biological tumor aggression. The Ki-67 expression is an important prognostic factor in meningioma progression group.