Relevance. The success of treatment of children with hepatoblastoma (HB) is associated primarily with the optimization of diagnostic and therapeutic strategies. The introduction of a system of therapeutic definition of a risk group developed by the International Society for the Study of Liver Tumors in Children’s Hepatic tumors International Collaboration (CHIC) in patients with HB allows for effective risk stratification. Patients of the very low-risk group have a favorable prognosis and, unlike patients of other groups, they can perform surgery at the 1st stage, and children from the very low-risk group with a “pure” fetal version of the morphological structure of the tumor can be cured without chemotherapy – only by surgical method. This article presents an analysis of a series of observations of children with HB very low-risk. Methods and patients. A retrospective analysis of the data of 138 patients who received treatment at the Research Institute of Pediatric Oncology and Hematology of N.N. Blokhin National Medical Research Centre of Oncology of the Ministry of Health of Russia from January 2006 to February 2018, all patients underwent examination in the following volume: computed tomography (CT) of the chest, ultrasound of the abdominal cavity and retroperitoneal space, CT and/or magnetic resonance imaging of the abdominal cavity with contrast enhancement. Serum levels of human chorionic gonadotropin and alpha-fetoprotein (AFP) were measured. The prevalence of tumor lesions was retrospectively evaluated using the PRETEXT system (Pre-Treatment Extent of Disease, assessment of the prevalence of the tumor process before treatment, 2017 version). Based on the data obtained, 18 (13 %) patients with hypertension were identified in the very low-risk group using the CHIC stratification system. Of 18 (100 %) patients of the very low-risk group, 8 (44.4 %) received therapy in the interval from January 2006 to October 2010 according to the treatment protocols of the SIOPEL group. The treatment included a combination of neoadjuvant chemotherapy with delayed surgery and adjuvant chemotherapy. Since November 2010, the Research Institute of Pediatric Oncology and Hematology adopted a protocol for the treatment of children with hypertension, suggesting the possibility of performing surgical treatment at the 1 st stage in patients with a localized stage of the disease with the spread of PRETEXT I/II. From December 2010 to November 2018, 10 (55.6 %) patients from the very low-risk group were operated on at the 1 st stage. A tumor biopsy was not performed before the intervention. After a histological examination, 4 (22.2 %) patients had an epithelial variant of the structure of HB that did not meet the criteria of a “pure” fetal variant. He was given adjuvant chemotherapy according to the SIOPEL protocol. And in 6 (33.3 %) patients, according to the results of a morphological study, the HB structure variant was interpreted as a “pure” fetal variant. Further therapy in this group of patients was not performed. The analysis of the results of treatment of these 6 patients without the use of chemotherapy is presented in our article. Results. The average age of patients is 3.7 (1–6) years, the median is 3.7 ± 2.0. Boys/girls – 4:2. In all cases, there was an asymptomatic course of the disease, a neoplasm was detected by chance during an ultrasound scan. All children had an elevated AFP level in the range of 95.2–695 (286.0 ± 116.8) IU/ml. Distribution according to PRETEXT I/II – 2 (33.3 %) and 4 (66.7 %) patients, respectively. Patients did not have additional PRETEXT criteria and metastases. Surgical treatment was performed by the laparoscopic method in 2 of 6 patients. Scope of operation: right-sided hemihepatectomy – 3, left-sided – 1, bisegmentectomy – 1, atypical resection – 1. Lymphatic dissection in the area of the hepatoduodenal ligament was not performed. There were no complications of treatment and repeated surgical interventions. The radicalness of the intervention in the volume of R0 was confirmed by histological examination in all patients. Morphological examination in all cases revealed a “pure” fetal version of the structure of the tumor. All patients are alive without signs of relapse at follow-up periods of 14.7 to 59.2 (32.0 ± 18.7) months. Conclusion. Using the system of therapeutic stratification into risk groups CHIC allows you to effectively distinguish patients with very low-risk groups, and for some children with a “pure” fetal version of the histological structure of the tumor, only the surgical approach can be used for treatment. At the same time, the short observation period for the patients and their small number do not allow us to draw final conclusions and dictate the need for a multicenter study. It should be noted that this cohort of patients requires careful observance of the post-therapeutic observation algorithm.

Congenital mesoblastic nephroma (CMN) is a rare primary kidney tumor in young children, characterized by intermediate biological behavior. The main treatment method is the radical removal of the tumor. The purpose of this study is to analyze our own experience in the treatment of patients with a diagnosis of CMN. Parents of patients agreed to the use of information about them, including photographs, in scientific research and publications.

О bjective is to evaluate the rate of bladder cancer in children and adolescents, characteristics of its histological variant, and treatment approaches. Materials and methods. A review of international literature on the problem of bladder cancer in children and adolescents as well as our own clinical observations of this pathology in 7 male patients aged 5–17 years in the period from 2012 to 2017 are presented. Results. According to the literature data and our own clinical observations, bladder cancer in children and adolescents is a rare pathology and it is a well-differentiated transitional cell carcinoma, localized, with favorable prognosis and rare recurrence. Treatment approach for bladder cancer in children and adolescents is the same as in adults, and usually is limited to transurethral resection of the bladder tumor. Conclusion. These observations serve as a reminder that bladder cancer can occur in children and adolescents, as well as in adults, which should elevate oncological vigilance among general practitioners.

Solid pseudopapillary tumor of the pancreas is a rare malignancy first diagnosed in a 19-yearold patient in 1927 and first described by Frantz in 1959. He reported the case of the 2-year-old child who died undergoing pancreatoduodenectomy. Our review included 36 papers: 5 published in Russian and 31 — in English. On the basis of the analyzed data we can conclude that the solid pseudopapillary pancreatic tumors in pediatric patients are characterized by slow growth and, as a rule, favorable prognosis. The chemotherapy is rarely performed due to the lack of tumor sensitivity to the drug treatment; the radical removal of the tumor is the main criterion for treatment success. Accurate preoperative diagnosis is extremely important for planning surgical treatment because patients who underwent radical surgery live for many years with no evidence of recurrence of the disease.

The paper describes the personal experience with one-stage operations for bilateral nephroblastoma (BN) in children. In 2000 to 2012, the Research Institute of Pediatric Oncology and Hematology, N.N. Blokhin Russian Cancer Research Institute, performed one-stage surgical interventions in 21 (26.2 %) children with BN. Their age ranged from 10 months to 5 years. The one-stage surgery as bilateral nephrectomy was made in 9 children. Nephrectomy with one-stage resection of the contralateral kidney was carried out in 4 children; 4 patients underwent one-stage surgery as resection of one kidney and biopsy of the other and 4 patients had nephrectomy and biopsy of the second kidney. BN is a rare disease as suggested by the data available in the world literature; each new report on patients with BN is of great scientific and practical interest. The rate of BN is 4 to 10 % of all kidney cancers in children. Synchronous and metachronous kidney injuries are encountered in 5–7 and 2–3 % of cases, respectively. Bilateral renal involvement is more commonly diagnosed in younger children. The major peak incidence of BN occurs from ages 3 to 5 years. The disease is rarely diagnosed in children above 10 years. Boys and girls are equally frequently ill.

The paper describes the personal experience with one-stage operations for bilateral nephroblastoma (BN) in children.In 2000 to 2012, the Research Institute of Pediatric Oncology and Hematology, N.N. Blokhin Russian Cancer Research Institute, performed one-stage surgical interventions in 21 (26.2 %) children with BN. Their age ranged from 10 months to 5 years. The one-stage surgery as bilateral nephrectomy was made in 9 children. Nephrectomy with one-stage resection of the contralateral kidney was carried out in 4 children; 4 patients underwent one-stage surgery as resection of one kidney and biopsy of the other and 4 patients had nephrectomy and biopsy of the second kidney.BN is a rare disease as suggested by the data available in the world literature; each new report on patients with BN is of great scientific and practical interest. The rate of BN is 4 to 10 % of all kidney cancers in children. Synchronous and metachronous kidney injuries are encountered in 5-7 and 2-3 % of cases, respectively. Bilateral renal involvement is more commonly diagnosed in younger children. The major peak incidence of BN occurs from ages 3 to 5 years. The disease is rarely diagnosed in children above 10 years. Boys and girls are equally frequently ill.

Background: Neuroblastoma is one of the most common tumors in children occupying the third place among all malignant neoplasms, trailing only the tumors of the central nervous system and soft tissue sarcomas. Survival in patients with high-risk neuroblastoma remains unsatisfactory. Objective: Improvement of the treatment results in patients with high-risk neuroblastoma. Methods: The study included 32 patients with high-risk neuroblastoma who received treatment at our clinic from 2009 to 2016: 21 (65.6%) boys and 11 (34.4%) girls aged 1.7–15 years (mean age 4.6±3.3 years). The median follow-up time was 19.8 months. Patients were divided into 2 groups depending on the regimens of induction polychemotherapy (PCT): in group I (n=19, 59.4%) patients received chemotherapy including topotecan, cyclophosphamide, vincristine, doxorubicin, cisplatin, etoposide; in group II (n=13; 40.6%) — threosulfan, vincristine, doxorubicin, cyclophosphamide, platidiam, etoposide, carboplatin. In both groups, therapy also included surgical treatment, high-dose CT, radiation therapy (RT), and biotherapy with ATRA. A part of patients from group I (n=4; 21%) who did not attain complete response to induction chemotherapy received systemic radiotherapy with 131I-MIBG. Results: The immediate efficacy (the ratio of the number of complete and partial effects obtained) of induction chemotherapy in the group I was 94.7% (n=18), in the group II — 84.6% (n = 11). Bone marrow sanation during induction chemotherapy was registered in 10 (71.5%) patients of group I after 1 course. In the remaining patients of group I, bone marrow sanation was detected after 2–5 courses of polychemotherapy. Bone marrow sanation after the first course of chemotherapy was revealed only in 4 (30.8%) patients of group II; in 2 (15.4%) patients bone marrow sanation was not detected. 2-year overall survival (OS) of patients with stage 4 in the group I was 65.6±14%, in the group II — 43.1±14.7%. The 2-year event-free survival (EFS) rate in the group I was 33.4±14.5%, in the group II — 23.1±11.7%. When performing single-factor regression analysis, the significant correlation between systemic radiotherapy and the absence of progression or relapse of the disease was revealed. Radical surgery does not affect the prognosis of the disease. Conclusion: The induction regimen used in group I showed a higher efficacy: OS and EFS rates in group I were higher. Patients with an active residual tumor tissue who completed the induction chemotherapy course were indicated a systemic radiotherapy with 131I-MIBG. The surgical treatment should be performed with organ-preservation approach.

The surgical method is extremely important in the structure of modern multimodal treatment strategies children with tumors of the thoraco-abdominal localization. Progress conservative antitumor therapy has helped change the outlook in pediatric oncology: the desire for the implementation of expanded combined operations (neuroblastoma, nephroblastoma and germ cell tumors) to conserving surgery. Surgery for each type of solid tumors should be standardized and, at the same time, take into account the individual features of the biology of cancer. The results of molecular genetic studies have modified the scope of surgical intervention in neuroblastoma and nephroblastoma. Questions remain in timing of transactions for the maximum effect of chemotherapy and drug resistance, as well as the feasibility of expanding operations in nephroblastoma and liver tumors. There is a positive experience of liver transplantation for hepatoblastoma and kidney transplantation with bilateral nephroblastoma. Endosurgical technology widely used in the diagnosis and surgery of neuroblastoma, renal tumors, liver, pelvic and lung tumors. The current strategy of child thoraco-abdominal cancer surgery is to seek to implement and highly functional organ-based operations according required cancer radicalism.

The autors report original date on the combined use of videosurgery and open surgical intervention in 3 patients. One (1 yr 10 mo) had neuroblastoma in the posterior mediastinum spreading to the retroperitoneal region, another (5 yr) presented with neuroblastoma in the thoracic aperture region spreading to the neck, the third one (14 yr) suffered limphoepithelioma-like cancer of the thymus. The combined treatment permits to optimize the surgical procedure and avoid additional use of thoraco- and laparotomy.

The autors report original date on the combined use of videosurgery and open surgical intervention in 3 patients. One (1 yr 10 mo) had neuroblastoma in the posterior mediastinum spreading to the retroperitoneal region, another (5 yr) presented with neuroblastoma in the thoracic aperture region spreading to the neck, the third one (14 yr) suffered limphoepithelioma-like cancer of the thymus. The combined treatment permits to optimize the surgical procedure and avoid additional use of thoraco- and laparotomy.