Introduction. Retinoblastoma (RB) is a malignant tumor of the retina, the survival rate for the intraocular form reaches 99 %. According to the researchers, the risk factors for the occurrence of refractory or recurrent forms of RB are the size of the tumor at primary diagnosis (more than 15 mm), the child's age at the onset of the disease (up to one year), bilateral RB, and the presence of subretinal and vitreal screenings. If methods of local destruction of the tumor are not applicable for the successful treatment of intraocular refractory or recurrent RB, then they resort to the second line of polychemotherapy as an alternative to enucleation. New versions of local chemotherapy and radiation therapy (gamma knife) are being developed and applied. Nowadays, researchers have a negative attitude towards traditional radiation therapy (EBRT) as a method of organ-preserving treatment due to serious consequences (asymmetry of the facial skeleton and second radio-induced tumors).
Aim of the study — to increase the effectiveness of organ-preserving treatment in patients with refractory or recurrent intraocular RB.
Materials and methods. In the period from 10.2018 to 12.2019 at the N.N. Blokhin National Medical Research Centre of Oncology it was received three-component selective intra-arterial chemotherapy (SIAC) in 15 patients (15 eyes) aged 11 to 52 months. Eyes initially affected by RB (n = 15), according to the IIRC (Murphree) classification, had the following groups: group B in 1 case, group C in 3, group D in 7, and group E in 4 eyes. It should be noted that all patients initially received intensive combined conservative therapy: in 11 (73 %) of 15 cases — systemic chemotherapy VEC; in 13 (86 %) of 15 — SIAC with melphalan, in all cases, additionally, two-component SIAC was used in combination with melphalan with topotecan. In some cases, local therapy in the form of intravitreal chemotherapy (IVIC) was added to the treatment of 6 (40 %) of 15 patients in the form of melphalan monotherapy and in one case (6 %) a doublet was used in combination with melphalan and topotecan. Also, in some patients, additional local ophthalmic therapy was used: transpupillary thermotherapy (TTT) in 6 out of 15 patients, including in combination with cryotherapy (CT) in 1 patient and in combination with brachytherapy (BT) in one case. At the same time, incomplete tumor regression (refractory form of the disease) was noted in 7 out of 15, and a recurrent course of the disease — in 8 out of 15 patients. Incomplete tumor regression and recurrent RB were the reasons for the appointment of a three-component SIAC using carboplatin, melphalan and topotecan, in combination with IVIC with pronounced endophytic growth of RB, as an alternative to irradiation and enucleation of the eye.
Results. The average number of three-component SIAC courses was 1.46 ± 0.63 (rang 1—3). The combination of SIAHT with IVHT was performed in 3 out of 15 patients. All children (n = 15) are alive with a median period of follow-up of23.92 ± 15.68 (10—64) months. One in 15 patients was lost from observation due to their parents’ desire to be treated abroad. It is known that the child is alive, but there is no data on the condition of his eyes. 9 out of 14 patients needed additional treatment after SIAC intensification. To consolidate the resulting effect as a full regression in 2 cases, the final IVIC courses were conducted (n = 2). In connection with the presence of residual tumor and/or intraocular progression and/or appearance of new lesions in 1 of 9 patients were IVIC and TTT, 2 of 9 — IVIC, SIAC, CT, TTT. In 4 out of 9 cases, enucleation was performed, and in 2 out of 4 — the operation was performed after continuing the attempt of organ-preserving treatment: after CT and TTT (n = 1) and IVIC, CT, TTT and BT (n = 1). No child was given ERBT. There were no cases of stroke after SIAC. We managed to save 10 (71.4 %) of 14 eyes with visual acuity: object vision in 4 (40 %) out of 10, eye fixation in 3 (30 %) out of 10, and light perception in 3 (30 %) out of 10 cases. The average follow-up period from the end of three-component SIAC in 14 patients was 13.57 ± 5.27 (6—22) months.
Conclusion. Thus, the three-component SIAC is effective and safe for patients with refractory and recurrent retinoblastoma, as evidenced by a high percentage of retained eyes and the presence of visual functions from light perception to object vision.

Aim of the study — to develop a strategy for the recruiting potential donors to the registry, which is based on the biological characteristics of russian populations.
Materials and methods. The object of the study was 35,117 potential donors of the hematopoietic stem cells of the registry of KRIHBT FMBA of Russia, recruited in 22 subjects of the Russian Federation.
Results. Based on a comparison of the HLA-A-B-C-DRB1 haplotype profiles of local donor populations, calculated using the EM-algorithm in the Arlequin v.3.5.2.2 software, with the profile of the pooled donor population of the registry, general requirements for the recruitment of potential hematopoietic stem cells donors to the registry were formulated.

Introduction. The need to perform nutritional support for children with cancer is widely recognized. The body of a child suffering from a malignant tumor needs additional amounts of energy and plastic substrates. Patients with signs of protein-energy insufficiency are at risk of developing complications in the early postoperative period. A significant role in compliance with early rehabilitation after surgery (ERAS) protocol is played by the method of perioperative analgesia. Caudal epidural block is the most widely used regional method of analgesia in children, allowing to start earlier enteral nutrition and prevent the development of postoperative paresis of the gastrointestinal tract (GIT), thereby speeding up the recovery of patients after surgery. In this study, we evaluated the effectiveness and safety of early enteral nutrition tactics in oncology children, in the postoperative period during laparoscopic surgical interventions, in order to prevent gastrointestinal paresis in combination with early activation of patients. In the present study, we evaluated the effectiveness of the tactics of choosing perioperative analgesia from the perspective of the possibility of early initiation of enteral nutrition in children with oncopathology, in the postoperative period after laparoscopic surgical interventions, in order to prevent paresis of the gastrointestinal tract in combination with early activation of patients.
Materials and methods. The study included 40 patients of the research Institute of Children's Oncology and Hematology of the Russian Ministry of health, ASA II—III, operated in 2017—2019for malignant abdominal tumors by laparoscopic method. Patients were divided into 2 groups randomly. The CB group included 23 children who were treated with caudal epidural block as a regional component of combined anesthesia (CB group, n = 23). The control group-GA included 17 children who underwent General anesthesia (group GA, n = 17).The analysis of the early postoperative period (day 1) was performed. Postoperative nutritional support was performed to prevent gastrointestinal paresis in combination with early activation of patients and consisted of early (from day 1 after surgery) enteral nutrition. We used a therapeutic mixture of Alfare® based on whey protein hydrolysate (for children under 1 year) and Peptamen® Junior based on hydrolyzed whey protein, a complete balanced dry mix (for children from 1 year to 10 years). The volume of enteral nutrition was calculated based on the number of calories per kg of body weight. We started therapeutic nutrition with volumes of 1/2-2/3 of the calculated volume and increased the volume to the required patient tolerance.
Results. Enteral nutrition in children in the CB group was connected from 4.7 ± 0.5 hours. In the GA group, enteral nutrition was switched on in 10 (59 %) patients 20 hours after the end of surgery. 5 children developed gastrostasis, which required medication to stimulate the gastrointestinal tract.
Conclusions. This study demonstrates that in the conditions of effective neuroaxial blockade in the perioperative period, it is possible to start enteral nutrition as early as possible, reducing to a minimum the frequency of postoperative intestinal paresis during laparoscopic surgical interventions, contributing to early and rapid recovery of patients.

Primitive myxoid mesenchymal tumor of infancy (PMMTI) is an aggressive tumor with a high rate of local recurrence, rare metastasis and poor response to chemotherapy.
PMMTI is a rare soft-tissue sarcoma that preferentially affects infants. It is isolated from the group of infantile fibrosarcomas or myofibroblastic tumors. PMMTI differs from other tumors in the clinical course, morphological features and primarily molecular genetic changes. ETV6-NTRK3 gene fusion is characteristic of infantile fibrosarcomas. However, it is not detected in patients with PMMTI. BCOR ITD had been described in patients with PMMTI and it allowed to define this tumor from the group of infantile fibrosarcomas.
Unified treatment approaches have not been identified for this tumor yet. Radical surgical removal is preferred treatment. BCOR ITD is a target. Nowadays search for targeted drugs is ongoing and it could help to solve the problem of PMMTI treatment.

Hemophilia B is a hereditary disease of the blood clotting system caused by a deficiency or molecular abnormalities of blood clotting factor IX. The main method of treatment is intravenous administration of coagulation factor IX concentrates. To optimize treatment and increase patient adherence to therapy, concentrates with a prolonged half-life have been developed.

Malignant neoplasms are the second most common cause of infant mortality worldwide. Nutritional deficiency occurs in approximately 60 % of children with cancer and contributes to a decrease in immune function, delayed wound healing, impaired drug metabolism, and a severe and recurrent course of infectious complications. Malnutrition has a particularly adverse effect on outcomes and is one of the main preventable causes of death in infants. Given the growing trend in the incidence of cancer in children of the first years of life, the lack of standards and recommendations for the therapeutic nutrition of these patients, the organization of nutritional support for infants in the context of pediatric oncology is becoming increasingly important. Our article presents current trends in the assessment and correction of the nutritional status of infants with cancer.

Rare bleeding disorders include inherited deficiencies of fibrinogen, factors (F)II, FV, FVII, FX, FXI, FXII, and FV + FVIII, as well as a multiple deficiency of vitamin K-dependent coagulation factors. Some of these deficiencies are more studied, due to the large number of patients, some are extremely rare, and so at this stage it is quite difficult for them to develop a universal approach to therapy and prophylactic treatment. The purpose of this review was to evaluate treatment options for these deficiencies.

The review article is about clinical experience in the use of modern tomographic methods (magnetic resonance imaging (MRI) and X-ray computed tomography (CT)) in the diagnosis and assessment of the progression of malignant bone neoplasms, summarizing the results of the largest studies demonstrating the comparative characteristics of the methods. Numerous data demonstrate high sensitivity of MRI and form the following diagnostic tasks that can be solved by this method: the involvement degree of soft tissues in the pathological process, damage to the neurovascular bundle, the articular surface, assessment of the extent of tumor in the bone marrow canal. At the same time, CT shows a higher sensitivity in assessing cortical destruction and the degree of matrix mineralization. The article discusses the variety of program sequences and modes of MRI scanning, the prospects of the method in assessing the prevalence, staging, and differential diagnosis of bone tumors.

Currently a priority in children oncology is a limb salvage treatment. Achieved in recent years advances in chemotherapy of malignant bone tumors, improved surgical techniques, and also introduction in orthopedics of the newest technologies allow to considerably expand the indications for endoprosthesis. A feature in cases in children of early age is the use of sliding implants type non-invasive and minimally invasive that subsequently allows gradual correction of leg length and avoid the various disorders of musculoskeletal system (shortened limbs, spinal deformity), thereby improving the quality of life of patients. In some cases, for example, when a tumor is localized in the upper limb region, the optimal solution may be the use of autologous grafts on microvascular anastomoses. In the case of tumor localization in the pelvic region, the use of implants made by means of 3D-modeling, in our opinion, is also an optimal solution.

This work is devoted to the analysis of the problems associated with the state of the oral cavity in patients healed from malignant neoplasms in childhood. The main diseases and pathological conditions that can develop in this population are considered. The risks of developing pathological changes in the oral cavity, their treatment and prevention are described. The issue of osteoradionecrosis is analyzed separately.