Introduction. Clear cell sarcoma of the kidney (CCSK) is a rare primary renal tumor in children. It is characterized by an aggressive course, rapid tumor growth, and a high propensity for metastasis. Clinical interest in CCSK stems not only from its aggressiveness as a distinct entity but also from the diagnostic challenges in differentiating it from other pediatric renal neoplasms. Standardization of diagnosis and optimization of therapy require the identification of molecular markers to improve differential diagnosis with other rare renal tumors. A comprehensive approach – from early detection by pediatricians to precise molecular genetic testing – is essential to improve prognosis.

The purpose of the study – to evaluate the clinical, morphological, and molecular genetic features of CCSK.

Materials and methods. We conducted a retrospective single-center study of children with CCSK who received treatment at the Research Institute of Pediatric Oncology and Hematology named after Academician L.A. Durnov, N.N. Blokhin National Medical Research Center of Oncology, Ministry of Health of Russia, between September 2009 and December 2023.

Results. Prognostic factors assessed included sex, age at diagnosis, primary tumor volume, and molecular genetic characteristics. The cohort was predominantly male (15/22, 68 %) compared with female (7/22, 32 %). Median age at diagnosis was 29 (17–44) months, and median primary tumor volume was 543 (368–748) cm3 . All tumors were unilateral (right-sided – 45 %, left-sided – 55 %). Localized disease was present in 21 (95.5 %) patients and metastatic disease in 1 (4.5 %); no pulmonary metastases were detected at diagnosis. No significant sex differences were observed in age or tumor volume (p > 0.05). At a median follow-up of 4.1 years, 6 events (27.3 %) and 2 deaths (9.1 %) occurred. Event-free survival (EFS) was 100 % at 1 year, 79.6 % (95 % confidence interval 63.4–99.9) at 3 years, and 72.4 % (95 % confidence interval 53.9–97.1 %) at 5 years. Overall survival (OS) was 100 %, 88.4 %, and 88.4 % (95 % confidence interval 74.3–100 %), respectively. Median EFS and OS were not reached; median time to event was 2.5 (1.7–5.6) years. Age < 2.7 years (cutoff – 32 months) showed a trend toward inferior EFS (p = 0.096, log-rank). No differences in EFS were found according to sex (p = 0.954), tumor volume (p = 0.446), or treatment protocol (Umbrella SIOP-RTSG 2016 (n = 12) vs. other regimens (SIOP-93-01, SIOP-2001; n = 10) (p = 0.6). Molecular genetic testing was performed in 7 patients (32 %); BCOR internal tandem duplication was identified in all 7 (100 %).

Conclusions. Age younger than 2.7 years may represent a potentially unfavorable prognostic factor in CCSK. The median time to first event of 2.5 years indicates that most relapses occur in the medium-term period after therapy completion.

Background. Morphological diagnosis of central nervous system (CNS) neoplasms is challenging due to significant inter- and intratumoral heterogeneity, as well as similarities in the histological features of different nosological forms. The resolving power of traditional methods (histological and immunohistochemical examination) is limited and does not always allow accurate identification of tumor molecular subtypes. The current World Health Organization (2021) classification of CNS tumors recommends complementing morphological diagnosis with molecular characterization, including DNA methylation profiling, which enables more precise diagnosis and optimizes subsequent therapy.

The purpose of the study – to develop and validate a DNA methylation-based classifier for CNS tumors using machine learning methods that ensures high predictive accuracy, reproducibility, and the ability to integrate both publicly available research data and locally collected samples from the N.N. Burdenko National Medical Research Center for Neurosurgery.

Materials and methods. Publicly available DNA methylation data generated on the Illumina 450K platform (2,801 samples), as well as locally collected data comprising 776 tumor and control brain tissue samples obtained using the Illumina EPIC platform at the N.N. Burdenko National Medical Research Center for Neurosurgery, were used for model development. To eliminate inter-platform variation (batch effect between 450K and EPIC), data normalization was performed. Training and test sets were prepared using stratified sampling. The model was built using a gradient boosting on decision trees algorithm for each tumor methylation class. Additional multiclass submodels were developed for specific tumor types, such as medulloblastoma and glioblastoma. Classifier performance was evaluated in terms of predictive accuracy and reproducibility.

Results. The classifier demonstrated high accuracy (» 0.95) in identifying both common and rare molecular classes of CNS tumors, including high-grade astrocytoma with piloid features. Incorporation of locally collected samples increased the method’s flexibility, improved representation of rare tumor types, and reduced the proportion of uncertain predictions.

Conclusions. The DNA methylation-based CNS tumor classifier developed at the N.N. Burdenko National Medical Research Center for Neurosurgery demonstrates high accuracy and is comparable to similar international models. The application of machine learning algorithms enhanced analytical reliability, while inclusion of in-house data enabled adaptation of the model to local sample characteristics. The presented approach is applicable for research, refining diagnoses in challenging cases, and implementing automated molecular diagnostic procedures for CNS tumors.

Introduction. Medulloblastoma is the most common malignant central nervous system tumor in children, representing a molecularly heterogeneous group of neoplasms (SHH, WNT, Group 3, Group 4 subtypes). Germline mutations in predisposition genes (PTCH1, SUFU, TP53, APC, BRCA2, PALB2, ELP1, GPR161) are identified in 5–15 % of patients, predominantly in SHH and WNT subtypes.

The purpose of the study – to develop a screening algorithm with a risk stratification scoring system for hereditary medulloblastoma variants to rationally select patients for genetic testing.

Materials and methods. The study included a cohort of 26 patients with medulloblastoma aged 0 to 18 years who received chemotherapy in 2024–2025 at V.F. Voyno-Yasenetsky Scientific and Practical Center of Specialized Medical Care for Children. Molecular subgroup determination was performed using NanoString technology or DNA methylation profiling. Genetic counseling was provided to all patients. Germline mutations in DNA extracted from peripheral blood were analyzed in 11 patients using parallel sequencing (whole exome sequencing) and Sanger sequencing.

Results. Molecular classification was performed in 20 patients: SHH – 38 %, WNT – 5 %, Group 3 – 24 %, Group 4 – 29 %. Genetic testing was conducted in 11 patients, with pathogenic germline variants identified in 6 (55 %): Gorlin syndrome (n = 2), Li–Fraumeni syndrome (n = 1), Turcot syndrome type 2 (n = 1), Fanconi anemia/PALB2 (n = 1), ELP1 mutation (n = 1). Hereditary forms were exclusively found in SHH/WNT subtypes (100 %). Patients with pathogenic variants scored ³ 4 points. No pathogenic variants were identified in Group 3 and Group 4 cases.

Conclusions. Genetic counseling with testing should be considered a standard procedure in the management of patients with SHH- and WNT-subtype medulloblastomas. The developed scoring system enables detection of 90–95% of hereditary forms while testing only 30–40 % of patients, improving diagnostic efficiency and optimizing resource utilization.

Background. According to international statistics tumors of the central nervous system take a leading position in the structure of childhood cancer morbidity. The use of a multimodal strategy of anticancer therapy today allows achieving a high level of long-term survival, but often with severe variants of long-term toxicity. The study of the health status of cured patients and assessment of their quality of life (QOL) in the aspects of searching for controllable factors to reduce treatment toxicity is a pressing problem in pediatric oncology and pediatrics.

Materials and methods. The study included 76 patients with a confirmed diagnosis of medulloblastoma (93.4 %) or atypical teratoid rhabdoid tumor (6.6 %), established at the age of up to 18 years, for which antitumor therapy was carried out. For assess to QOL, the Health Utilities Index questionnaire of Mark 2 and 3 versions (HUI2 and HUI3) was used, consisting of 15 questions. The impact of disease burden (histological tumor type, stage and type (primary tumor/relapse) of the disease, inclusion of high-dose chemotherapy, volume of radiation therapy and surgery) on the health attribute scores was analyzed.

Results. The median age of patients at the time of the survey was 11.7 years with a median interval after completion of specific treatment of 6.4 years. Respondents to the survey were patients’ parents (n = 37; 48.7 %) and/or the attending physician monitoring the child (n = 39; 51.3 %). The average time spent on filling out the questionnaire was 8.0 ± 3.0 min. The frequency of a decrease in the levels of health attributes according to the HUI2 and HUI3 systems were 47% and 53 %, corresponding to mild (66 % and 62 %), moderate (27 % and 26 %) and severe (7 % and 12 %) severity of disorders. Functional health disorders mostly concerned such QOL components as cognitive abilities, emotions, sensation, mobility, varying from moderate to severe. Metastatic stage of the tumor had statistically significant negative impact on mobility and ambulation (p = 0.02), self-care (p = 0.05) and dexterity (p = 0.01); patients with disease recurrence showed decreased cognition (p = 0.03) and emotional status (p = 0.002); the use of craniospinal irradiation was also associated with decreased cognitive abilities (p = 0.04).

Conclusions. Assessment of patients’ QOL using the HUI2 and HUI3 questionnaire is a simple and accessible method for routine use in clinical practice. Statistically significant deviations in health attributes were registered in children who underwent antitumor therapy for medulloblastoma or atypical teratoid rhabdoid tumor, while unfavorable risk factors were disease recurrence, metastatic stage of the disease and radiation therapy in the CSI. It is important to note that despite the high percentage of recorded deviations in the assessed health attributes, more than half of them corresponded to mild to moderate impairments. The most vulnerable components were the motor sphere and cognitive abilities. Given the small sample size, it is impossible to speak about a high degree of significance of the obtained results, which requires continuation of research in the specified cohort of patients, however, they coincide with international literature data. It should also be noted that the questionnaire provides an assessment of the health status of patients in a specific period, while it can change significantly over time and against the background of numerous factors, thereby determining the need for dynamic monitoring.

Surgical treatment of central nervous system (CNS) tumors in children presents a complex medical and social challenge, driven not only by the relatively low prevalence of this pathology in pediatric practice but also by the significant heterogeneity of the disease, owing to the variability of patient age, tumor location, and histopathological structure. Despite these challenges, recent decades have seen progress in improving overall survival in children with CNS tumors, driven by the introduction of a multidisciplinary, personalized approach into clinical practice, based on modern therapeutic protocols and integrating the efforts of specialists from various fields.

The introduction of molecular genetic tumor profiling methods has become particularly important in improving neuro-oncological care. The introduction of histological and molecular characteristics has become an integral diagnostic standard, allowing not only to establish a diagnosis, prognosis, and treatment strategy, but also to identify targets for targeted therapy.

We present an analysis of surgical interventions in children with CNS tumors at a multidisciplinary hospital in Moscow. Interdisciplinary collaboration among neurosurgeons, oncologists, neurologists, radiologists, pathologists, and other related specialists plays a key role in achieving optimal treatment outcomes and improving patients’ quality of life.

The study included 417 children who underwent surgery for CNS tumors at the Morozov Children’s City Clinical Hospital of the Department of Health of Moscow. The analysis included tumor resection volumes according to the Gnekow classification, CSF shunt procedures, complications, tumor location, histomolecular variants, overall survival, and mortality in this cohort of patients.

Introduction. When treating germ-cell tumors (teratomas) in newborns it is not always possible to avoid breaking of continuity of the tumoral tissue (such as capsule rupture or spillage of the cysts). There exist several procedures described and used, requiring intentional disruption of tumoral integrity: intrauterine punctures of large cysts, EXIT-procedures. The question concerning possible increase of tumor recurrence risk in such cases remains disputable up to date.

The aim of study – based on 19 years’ experience of two clinics, to assess incidence of tumoral rupture cases during treatment of teratomas in newborns, analyzing their causes, possibilities of prophylaxis, and prognostic value.

Materials and methods. A retrospective analysis of medical documentation and follow-up data was performed concerning 75 newborns with teratomas from one surgical and one oncological clinic in Saint Petersburg during a period of 2005–2023. Patients with teratomas of different localization were operated on the day of life 0–14, from whom 8 subsequently developed a local recurrence within 2–18 months after surgery. The fact of tumoral rupture was established in 25 (33.3 %) children: with sacrococcygeal – 23 (92 %), neck – 1 (4 %), and abdominal localization – 1 (4 %). Those cases included an intrauterine cyst puncture (n = 1), partial resection of a giant sacrococcygeal teratoma during an EXIT-procedure (n = 2), rupture of tumoral membranes during delivery (n = 3), intentional puncture or unwilling spillage of the cysts during surgery (n = 24), 4 babies having a combination of several variants of tumoral rupture at one time. After exclusion of cases with unknown follow-up data total of 63 patients were investigated: 22 with tumoral rupture (including 3 with subsequent relapses) and 41 without tumoral rupture (including 5 with subsequent relapses). Statistical assessment was provided.

Results. The predominant variant appeared to be intraoperative rupture of teratomas: 24 (32 %) cases, among them 83 % representing unintentional spillage of the cysts because of difficulties of visualization of their thin walls during dissection. The statistical analysis performed revealed no correlation between tumoral rupture and subsequent recurrence of teratoma in our study (p = 1.0; Fisher’s exact test).

Conclusion. The prognostic value of tumoral rupture and spillage in neonatal teratomas treatment deserves, perhaps, some further interpretation, requiring more investigation using larger cohorts of patients. At the same time, the results of current study could probably serve to justify some antenatal interventions, EXIT-procedures, as well as intentional cyst punctures in certain challenging cases during treatment of teratomas in newborns.

Introduction. Сontinuous infusion of factor concentrate makes it possible to achieve stable activity of the deficient factor over a long period of time and appears to be an attractive alternative to bolus administration of concentrate as part of perioperative prophylaxis.

The aim of the study – evaluation of pharmacokinetic parameters when using continuous factor infusion VIII and IX concentrates in children with hemophilia A and B in the perioperative period in real clinical practice.

Materials and methods. A retrospective analysis of medical records data from children with hemophilia A and B who underwent surgical treatment with continuous infusion of factor VIII concentrate was performed at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology from 2015 to 2024. The following pharmacokinetic parameters were also assessed during administration (ACL TOP 700): activity of factors VIII and IX before the administration of concentrate, 30 min after the administration of the concentrate dose and the start of surgery, at finish of the surgery and also every 24 h from the time of surgery until the factor infusion was stopped (single-stage clotting method for determining HemosIL, Instrumentation Laboratory, USA), activated partial thromboplastin time and thromboelastogram. An assessment of bleeding, the presence of an inhibitor to the factor and thrombosis in the early postoperative period was carried out.

Results. The study included 5 patients with hemophilia A and 2 patients with hemophilia B. Before surgery, all patients received bolus infusion at a dose of 1000 to 5000 IU with subsequent transition to continuous factor infusion at a median dose of 5 IU/kg/h (range – 3.5 to 9,0 IU/kg/h). All patients had stable pharmacokinetic parameters; the activity of the deficient factor was in the expected range. No patient had complications of surgery with bleeding or thrombosis.

Conclusions. In real clinical practice, when using continuous infusion of factor VIII concentrate at a dose of 3,5–9,0 IU/kg/h, stable pharmacokinetic parameters are achieved, allowing its use in children when planning perioperative management.

Pulmonary embolism (PE) is a life-threatening condition characterized by the blockage of one or more branches of the pulmonary artery by a thrombus. This condition can be asymptomatic or lead to rapid death. Making an accurate diagnosis can be difficult for a doctor because PE is a relatively rare condition in children. This review summarises the available data on PE in children. The article discusses epidemiology, etiology, risk factors, pathogenesis, clinical presentation, diagnosis and treatment.

Retinoblastoma (RB) is one of the most common malignant intraocular tumors in children. The incidence rate of RB in the world is 1 case per 16,000–18,000 live newborns. In the absence of access to genomic biomarkers, ophthalmologists strictly rely on clinical signs when making therapeutic decisions. Knowledge of the genetic nature and molecular features of RB can provide a more objective understanding of the disease as a whole, conducting early diagnosis, predicting the course of the disease, including assessing the therapeutic response of the tumor to treatment. This makes it possible to individualize patient management tactics aimed at preserving life, and, importantly, preserving the organ of vision and its function. Until recently, molecular and genomic profiling of RB was limited exclusively to enucleated eyes, which was explained by the prohibition of performing a direct tumor biopsy due to the risk of extraocular spread. An alternative to a direct biopsy is a liquid biopsy. Its diagnostic potential is based on the presence of extracellular DNA in body fluids, including those of tumor origin. For patients with RB, the main material used to search for germinal mutations is blood. However, for the analysis of somatic mutations in a tumor, in the case of RB, blood is not a reliable enough material. The article provides an overview of publications on the possibilities of genomic profiling of RB using liquid biopsy. The material of choice for liquid biopsy in the case of intraocular RB was the aqueous humor of the anterior chamber of the eye in order to study the molecular genetic nature of RB in vivo.

Despite the use of multimodal therapy in patients with high-risk neuroblastoma (NB), the prognosis in high-risk patients remains unfavorable. Immunotherapy with monoclonal antibodies (mAb) in the post-consolidation period of treatment of high-risk NB has marked significant progress in improving the prognosis for patients who have achieved a good response to first-line therapy. Currently, the US Food and Drug Administration has approved three mAb drugs for the treatment of patients with high-risk NB: dinutuximab (Ch14.18), dinutuximab beta (Ch14.18/CHO), and naxitamab (Hu3F8). This publication is devoted to a review of the clinical use of the humanized mAb Hu3F8, the efficacy of which has been demonstrated in clinical trials.

Infant-type hemispheric gliomas are a rare group of central nervous system tumors occurring in very young children. Contemporary diagnostic approaches, including prenatal neuroimaging, molecular genetic profiling, and the use of targeted therapy, make it possible to improve prognosis and increase patient survival while preserving quality of life. The present clinical case illustrates the features of diagnosis and treatment of infant-type hemispheric glioma with NTRK1 gene rearrangement in a child during the first year of life and also highlights the challenges associated with selecting an optimal therapeutic strategy.

Background. Extraneural myxopapillary ependymomas (MPE) of the sacrococcygeal region are ultra-rare ependymal tumors with a marked pediatric predominance; no more than 36 pediatric cases have been reported in the world literature.

Materials and methods. We performed a retrospective analysis of 5 pediatric patients with extraneural MPE diagnosed at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology (Moscow) between 2015 and 2024. All patients were girls, the median age at diagnosis was 8.3 years (range – 4.9–15.3 years).

Results. In 4 (80 %) of 5 patients, the tumor was located subcutaneously in the sacrococcygeal or intergluteal region; in 1 case it was presacral. A primary diagnostic error was recorded in 3 (60 %) patients, incorrect diagnoses were soft tissue sarcoma, primitive neuroectodermal tumor/immature teratoma, and clear cell ependymoma. All 5 tumors were morphologically consistent with MPE WHO grade 2 with diffuse GFAP expression. Molecular profiling by targeted gene expression profiling (NanoString technology) was performed in 4 of 5 (80 %) patients and confirmed the diagnosis of MPE in all cases. Radical resection was achieved in 4 patients (80 %); none of them developed recurrence. The single patient with R+ resection demonstrated disease progression. At a median follow-up of 43.0 months, all 5 patients are alive.

Conclusions. Extraneural MPEs are characterized by a high rate of diagnostic errors and require mandatory histological review in a specialized reference center. Molecular genetic profiling using NanoString technology confirms the diagnosis and demonstrates the molecular relatedness of extraneural MPEs to their spinal counterparts. Radical resection is the key prognostic factor. Because of the risk of late metastatic spread, lifelong follow-up is required.

Diffuse infiltrative retinoblastoma (RB) is a rare form of RB, which is the most malignant, first described by N. Ashton in 1958. Its occurrence among all forms of RB according to previously published articles ranges from 2.0 to 4.6 %. The article presents a unique case of diffuse infiltrative RB with extensive damage to the central nervous system, which resulted in remission in a child with a primary diagnosis of the disease at the age of 11 years.

This article presents a rare clinical observation of an aggressive course of papillary thyroid carcinoma in a 15-year-old female patient, featuring distant liver metastasis, which is unique for the pediatric age group. All stages of diagnosis are described. Data on the comprehensive treatment provided are presented: surgical (radical thyroidectomy with bilateral selective neck lymph node dissection) and radioiodine therapy (RAIT) (4 courses with a total activity of 15 GBq). Following RAIT, complete regression of metastases in the lungs and cervical lymph nodes was achieved, and stabilization of the liver lesions was noted, with a decrease in radiopharmaceutical uptake according to scintigraphic studies and a reduction in thyroglobulin levels by more than 3.5 times. The conclusion is made about the possibility of achieving high efficacy of RAIT in the presence of metastases not only to the lungs but also to the liver. The importance of a multidisciplinary approach and oncological vigilance in patients with high-risk factors for disease recurrence and progression is emphasized.

Introduction. Malignant neoplasms of the kidney remain one of the most significant problems in modern oncourology and pediatric oncology. According to the World Health Organization (2024), more than 430,000 new cases of malignant renal neoplasms are registered worldwide annually, of which approximately 5–7% occur in patients under 18 years of age.

The purpose of the study – to demonstrate how intelligent software solutions improve diagnosis and treatment planning in children and adolescents with renal neoplasms, based on clinical cases from real-world practice.

Materials and methods. A series of three cases examined and treated at the Stavropol Regional Children’s Clinical Hospital and the N.N. Blokhin National Medical Research Centre of Oncology, Ministry of Health of Russia is presented. Medvision AI (automated segmentation and 3D modeling), standard computer/magnetic resonance imaging protocols, and histological verification were used.

Results. Intelligent tools provided more accurate delineation of tumor contours compared with analogs (Viewer “Kometa 3Di PACS”, Radiant), clarified relationships with vascular structures, and enabled quantitative assessment of lesion volume. Preoperative diagnosis fully matched morphological findings in 3 out of 3 cases, without specification of the histological tumor subtype. In one case, 3D planning changed the surgical strategy in favor of organ-sparing resection. No intraoperative complications were observed; visualization reduced the number of intraoperative errors and increased concordance between the surgical plan and the surgeon’s actual actions.

Conclusions. Integration of Medvision AI into routine practice is feasible, safe, and clinically beneficial: it assists in determining the extent of surgical intervention and supports personalized decision-making. Prospective multicenter studies are required to quantitatively assess its impact on outcomes and resource efficiency.