Introduction. Renal cell carcinoma (RCC) is a rare malignant renal tumor in children, which accounts for 2–4 % of pediatric and adolescent’s kidney malignancies. A number of recent studies have shown that RCC developing in pediatric age differs in the spectrum of histological variants, clinical course and prognosis from RCC in adult patients.

The aim of the study – retrospective analysis of the clinical and morphological characteristics of RCC, as well as the results of therapy of patients with a diagnosis verified in the Department of Pathology in Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Ministry of Health of Russia (Center).

Materials and methods. Retrospective analysis of patients with a histologically confirmed diagnosis RCC for the period 01.2012–05.2022 was done. During the specified period of time in the Department of Pathology in Center 42 patients with a confirmed diagnosis of RCC aged 0 to 18 years were registered. Out of 42 registered patients with RСС, 28 patients with known clinical data were included in this analysis, of which 11 patients underwent primary surgical treatment in Center. Demographic characteristics, clinical data, morphological variants of RCC, the volume of therapy performed, including the features of the performed surgical intervention were analyzed. The assessment of stage was carried out according to the TNM classification. Patients were treated according to the protocols of the SIOP-RTSG group (SIOP 93-01, SIOP-2001, SIOP-RTSG-2016). The analysis of the results was carried out on 01.06.2022.

Results. In the general group of patients (n = 42), the distribution by histological types was presented as follows: papillary type – in 16/42 (38.0 %), translocation type – in 12/42 (28.6 %), clear cell type – in 5/42 (11.9 %), chromophobic type – in 4/42 (9.5 %), RCC with succinate dehydrogenase deficiency – in 2/42 (4.8 %), translocation type in combination with papillary type – in 1/42 (2.4 %), tubulocystic type – in 1/42 (2.4 %), unspecified type – in 1/42 (2.4 %). A subsequent in-depth analysis was performed on a group of 28 patients. The median age at the time of diagnosis of RCC was 11.0 years (range – 3.0–16.9). The male:female ratio was 1.1:1. The median tumor volume (n = 27) was 44 cm3 (range 1.8–547.7 cm3 ). The clinical picture included palpable formation in the abdominal cavity (n = 5), intoxication syndrome (n = 5), pain (n = 4), enuresis (n = 1), macrohematuria (n = 1), in 12 cases the tumor was detected accidentally. The duration from the onset of the first symptoms/detection of the tumor to the diagnosis was 2.5 months (range 0.5–40.3 months). Distribution by clinical stages according to the TNM system: stage T1 – 22 (78.5 %) cases, T2 – 4 (14.3 %) cases, T3 – 1 (3.6 %), Tx – 1 (3.6 %) case. According to the results of postsurgical staging, the following distribution by stages N was noted: N0 – 15 (53.6 %) cases, N1 – 4 (14.3 %) cases, Nx – 9 (32.1 %) cases. Stage M0 – in 22 (79 %) patients, 6 (21 %) patients were not fully examined, the stage was treated as Mx, mainly due to the lack of data on osteoscintigraphy. It should be noted that proven distant metastases were not detected in any patient at the time of diagnosis. Preoperative polychemotherapy (PCT) without histological verification was performed in 9 (32.1 %) patients. When assessing the size of the tumor after preoperative PCT, a decrease in size was noted in 2 patients, the absence of size dynamics in 7 patients. Surgical treatment was performed in all patients. An initial thick-needle biopsy followed by surgery was performed in 6 (21.4 %) patients, 1 (3.6 %) patient underwent an initial laparoscopic biopsy of the affected retroperitoneal lymph node. In 1 (3.6 %) case, a biopsy was performed followed by chemotherapy. In 3 cases, the biopsy was uninformative and in 2 cases a second biopsy was performed. The primary surgery was performed in 11 (39.3 %) patients. R0 resection was achieved in 22 (78.6 %) cases, R1 resection was proved in 2 (7.1 %) cases, in 4 (14.3 %) cases the resection edges were not subject to evaluation (Rx). In 2 cases, complications of surgical treatment were noted: in 1 case, intraoperative tumor rupture, in 1 case – ischemic nephropathy after laparoscopic kidney resection. All patients were diagnosed morphologically in Center. Translocation RCC – 9 (32.1 %) cases and papillary RCC – 9 (32.1 %) cases prevailed in the group of 28 patients. The discrepancy of diagnoses/histological subtypes of RCC between the local pathomorphological laboratory and the reference in Center were noted in 7 (25 %) cases. The median follow–up of patients was 15.9 months (range 0.4–78.0 months). Of the 28 patients, 26 are alive (92.8 %). The progression of the disease was observed in 2 cases with the development of distant metastases in 1.6 and 12.8 months, these patients died.

Conclusion. RCC is a rare type of kidney tumor in children. Papillary and translocation variants of PCC are prevalent in the pediatric population. At the moment, radical nephrectomy with mandatory morphological examination of regional lymph nodes is considered as a standard treatment, while in some cases an organ-preserving operation may be considered. Interdisciplinary discussion of management tactics and surgical treatment in centers specializing in pediatric oncourology is mandatory.

Relevance. Currently there are various methods of organ-preserving treatment of retinoblastoma (RB), but nevertheless, eyeball enucleation remains one of the main methods of its treating. After removal of the eyeball, children face cosmetic problems such as anophthalmic syndrome, lag in the growth of orbital bones, as well as psychosocial problems. After the introduction of magnetic resonance imaging into a wide medical practice, children with RB began to undergo primary endoprosthesis of the orbit using porous polytetrafluoroethylene implants or non-porous silicone implants, which proved to be an effective method of cosmetic rehabilitation.

The purpose of the study – to present our own experience in the use of primary orbital endoprosthesis in children with RB with the use of a silicone implant.

Materials and methods. The study included 29 children (29 eyes) who underwent primary endoprosthesis of the orbit after enucleation for RB using a silicone implant (Plastis-M) wrapped in a dacron mesh. Written consent was received from all patients for the processing of personal data, diagnostic examination and treatment. The median age of patients at the time of enucleation was 32.7 (2–93) months. Silicone implants with a diameter of 16 mm (n = 4, 13.8 %), 17 mm (n = 13, 44.8 %) and 18 mm (n = 12, 41.4 %) were used. In most cases (n = 19, 65.5 %) enucleation was performed due to the inability to use organ–preserving treatment, due to the widespread intraocular tumor process, in 7 (24.1 %) cases enucleation was performed due to tumor progression against the background of ongoing treatment, and in 3 (10.3 %) – due to complications that occurred after treatment, namely subatrophy of the eyeball.

Results. A satisfactory cosmetic result and a symmetrical look were achieved in all cases. The difference in the endurance of the prosthetic and paired eyes according to exophthalmometry was up to 2 mm. The thickness of the well-developed musculoskeletal stump was 1.5 (0.84–2.74) mm.

Conclusions. A silicone implant wrapped in a dacron mesh endoprosthesis provides a stable and cosmetically satisfactory condition of the musculoskeletal stump in children with RB. Replacement of a silicone implant for cosmetic purposes is possible in children who are under regular dynamic control with complete remission of the tumor.

Retinoblastoma (RB) is one of the most common malignant neoplasms of the visual organ in children, with an established genetic factor in the development of the disease. The detection of mutations in the RB1 gene has been successfully carried out for many years, however, the development of technologies for DNA diagnostics of RB allows us to consider this disease not only as an independent tumor, but also as one of the manifestations of more complicated genetic syndromes involving a complex of genes. The correct genetic diagnosis is important to understand the prognosis of the health of a patient with RB and recommendations for his further observation, as well as a correct assessment of the risks of having children with the same pathology in the family.

Currently available methods of DNA diagnostics of the RB1 gene are new generation sequencing (NGS) and multiplex amplification of ligated probes (MLPA). However, in some cases, additional diagnostics may be required – a karyotype study or chromosomal micromatrix analysis (CMA). In this article we present a molecular genetic study of children with uni- and bilateral RB with an extended deletion at the RB1 gene locus. The aim of the study was determining of possible indications for the appointment of extended DNA diagnostics.

Background. The success of pediatric oncohematology makes the rehabilitation of cured patients more and more relevant. Physiotherapy for cancer patients is an underdeveloped method of treatment.

The purpose of the study – to analyze the use of physiotherapy techniques in the rehabilitation practice of pediatric oncologists, hematologists.

Materials and methods. The authors completed their research based on the materials of the activities of the Department of Physiotherapy of the Clinical Rehabilitation Research Center “Russian Field” for the period 2018–2021.

Results and discussion. Approximately 2,000 patients per year with oncohematological diseases during the period of remission receive evidence-based physiotherapeutic methods of treatment (electrotherapy, inhalations, magnetotherapy, balneotherapy, massage). Doctors note the effectiveness and safety of the therapy.

Conclusion. Knowledge of the evidence-based basis of physiotherapy treatment allows doctors to choose an adequate method and increase the effectiveness of rehabilitation.

Relevance. Malignant tumors among the children’s population is a relatively rare phenomenon. In the USSR, the form of state reporting for the analysis of morbidity provided for the collection of data in the first age group totaling from 0 to 29 years. Indeed, in this age group, malignant tumors are rare 10–15 cases per 100,000 children. Then, after the 35-year-old group, the risk of cancer increases by 10 % every year, and a five-year period gives an increase in the incidence rate by 50–70 %. The probability of malignant tumors in younger age groups differs hundreds of times from those who have reached the age of 70. In accordance with World Health Organization – IARC recommendations, the data in IARC monographs are summarized for 5-year-old age groups 0–4, 5–9, 10–14, 15–19, etc. The last open interval is 85+.

Prepared by the staff of the Laboratory of Oncological Statistics and the Children’s Department of the N.N. Petrov National Medical Research Center of Oncology together with Novel LLC, the completed topic of scientific development of the population children’s cancer registry at the federal district level, transmitted and accepted by the Ministry of Health of the Russian Federation, turned out to be unclaimed.

In February 2019, we formed a unified database of the Northwestern Federal District with a volume of more than 1 million 350 thousand observations, which made it possible to carry out a more detailed development of data on rare localizations: cancer of the heart, eye, thymus, including rare tumors that occur among children population (0–14 years old) and adolescents (15–17 years old). The purpose of the study is to study the patterns of dynamics of morbidity, mortality, the reliability of accounting for sick children (0–14 years old) at the population level, to calculate the survival rates of patients with all tumor localizations, taking into account gender, age, stage of the disease, histological forms and other parameters included in the registration form card (in accordance with the international standard of the Eurocare program). Results. From 2000 to 2018, 4970 children (0–14 years old) with malignant tumors were registered in the Northwestern Federal District of the Russian Federation, of which 3011 are subject to the staging of the tumor process. It is important to note that among all children of patients with malignant tumors, the five-year survival rate of stageable and non-stageable patients was close to 80 %. There is a high level of staging of patients of this group. Thus, patients with stage I of the disease had a five-year survival rate (2010–2014) – 96.3 %, with II – 91.0 % and only with stage IV – 50.9 %.

Conclusions. The creation of a children’s population cancer registry at the federal district level could significantly raise the level of primary registration of malignant tumors, eliminate losses and be able to calculate analytical indicators for rare childhood localization of malignant tumors.

Introduction. Liver tumors account for 1.1 % of all newly diagnosed neoplasms in children. The rarity of this pathology causes difficulties in differential diagnosis. Currently, magnetic resonance imaging (MRI) is the main and most promising method for diagnosing liver diseases. In our work, we decided to quantify the data from this study.

Purpose of the study – determination of the possibilities of quantitative assessment of multiparametric MRI data in the differential diagnosis of benign and malignant liver tumors in children.

Material and methods. 133 patients with 307 liver lesions aged from 5 months to 20 years were examined. All patients underwent MRI on high-field MRI machines using an extracellular contrast agent, which included T2 weighted images with and without suppression of the signal from adipose tissue, diffusion-weighted images with automatic calculation of maps of the apparent diffusion coefficient (ADC), T1 weighted images with suppression of the signal from adipose tissue before and after the introduction of a contrast agent (in the arterial, portal, venous and delayed phases). Quantitative characteristics of changes in signal intensity in the lesion, intact liver parenchyma, spleen, kidney, aorta, and inferior vena cava (IVC) were obtained. To level the influence of external factors, we used not the absolute values of the signal intensity, but the ratios: lesion/intact liver parenchyma, lesion/kidney, lesion/aorta, lesion/spleen, lesion/IVC. For each lesion, 5 coefficients were calculated in each of the sequences, with the exception of patients (n = 4) after splenectomy, in whom 4 coefficients were calculated. In addition, for images obtained after the injection of a contrast agent, the ratios of the signal on post-contrast images to the native phase were calculated. Quantitative parameters such as the maximum size of the tumor, its volume and the age of the patient were included in the calculation. Tumors were represented by benign (n = 139) and malignant (n = 169) formations. The diagnosis of all malignant neoplasms and some benign ones was confirmed morphologically, benign ones – using MRI with intravenous contrast and dynamic observation.

Results. A mathematical model was built:

A = 1/(1+e^-Z),

where Z = 6,25019 + 1,03132 × S + 1,30077 × P_2le/li – 0,00459 × DC_le + 4,01375 × P_1le/a – 2,05533 × P_{art le/li} – 2,55823 × P_{port le/k} + 7,56980 × P_{del5 le/k} – 15,91047 × P_{del5 le/a}.

The model is informative and statistically significant (p < 0.001). If A > 0.5, it should be considered that the studied focus is of a malignant nature, if A ≤ 0.5, the formation is benign. Model sensitivity and specificity were, respectively, 0.947 and 0.917.

Conclusion. The mathematical model makes it possible to differentiate between malignant and benign formations with a high degree of informativeness, which is a priority task in detecting a mass formation in the liver.

Currently, the daily routine of a molecular pathologist is DNA methylation and RNA and DNA sequencing. The authors, from the standpoint of researchers and clinicians, explain the molecular methods used not only to diagnose brain tumors, but also to search for possible targets for therapy.

Neuroblastoma (NB) is the most common extracranial solid tumor of childhood affecting children from 0 to 14 years old. Despite the achievements of modern multimodal risk-adapted therapy, the prognosis in patients with high-risk NB remains unfavorable. Numerous research groups have shown that a good response achieved at the time of completion of the induction stage of therapy in this subgroup of patients correlates with survival rates. Thus, improving the response to induction therapy may be a potential mechanism for improving long-term survival rates. Over the past few decades, traditional approaches to cancer therapy have undergone a radical revolution, largely due to the development and implementation of the immunotherapy method. It is known that combined antitumor therapy is superior to monotherapy and is one of the tools for overcoming heterogeneous drug resistance. A vast number of preclinical studies has shown that GD2-directed monoclonal antibodies (mAbs) are able to enhance the cytostatic effects of chemotherapeutic drugs, which has become a promising model for clinical studies of various chemoimmunotherapy regimens, which have demonstrated convincing evidence of safety and an acceptable toxicity profile with an encouraging effect on objective response rates, overall and event-free survival in both patients with recurrent, refractory NB, and primary patients of the high-risk group.

The article discusses fundamental ideas about the synergistic interaction of GD2-directed mAbs in combination with cytostatic agents, the role of response to the induction stage of therapy and prospects for the use of induction chemoimmunotherapy as a method of improving postinduction response, event-free and overall survival in patients with NB.

Despite of good outcomes in treatment of patients with newly diagnosed Langerhans cell histiocytosis (LCH), recurrences have been reported in 29.9 % of patients. There are currently no generally accepted standards for the treatment of recurrences and refractory forms of LCH. The prognosis of patients, suffering from this pathology, remains unfavorable. Current treatment approaches of recurrences and refractory forms of LCH include using of BRAF- and MEK-inhibitors and cellular treatment technologies. The article provides a literature review of current approaches to the treatment of recurrences and refractory forms of LCH and identifies the prospects for further research.

Malignant neoplasms (MNP) of the gastrointestinal tract in children are extremely rare and account for 1.2 % of all MNP. According to world literature, the incidence of gastric cancer is no more than 0.05 % of all cases of MNP of the gastrointestinal tract in children. In national and foreign literature, only isolated cases of stomach cancer in children and adolescents aged 10 to 18 years are described. Clinical manifestations of the disease, as in patients over the age of 18, are non-specific – epigastric pain, loss of appetite, weight loss, ascites, anemia, melena and others. In this regard, the diagnosis occurs at the late stages of the disease and, therefore, is characterized by an unfavorable prognosis. Gastric signet ring cell carcinoma (SRCC) is an uncommon histologic subtype of adenocarcinoma and usually occurs in people aged 20 to 40 years. We would like to report an extremely rare case of SRCC in a 14-year-old child.

PROS (PIK3CA-Related Overgrowth Spectrum) encompasses vascular malformations, lipomatosis and other multiple congenital anomalies resulting from activating somatic mutations in the PIK3CA gene. PROS includes macrodactyly, hemimegalencephaly, muscle hemihypertrophy, facial infiltrating lipomatosis CLOVES, megalencephaly, vascular malformations (capillary, venous, lymphatic, arteriovenous and combined vascular malformations), skin disorders, epidermal nevi, etc.

The experts of the Russian Society of Pediatric Oncologists and Hematologists, Russian Association of Pediatric Surgeons and Russian Society of Medical Geneticists developed this consensus statement of diagnostics and treatment of PROS.