The incidence of esthesioneuroblastoma in children under 15 years of age is 0.1 per 100.000 children. Distinctive histological features of this tumor are diffuse accumulation of neuron-specific enolase, synaptophysin, chromogranin, and variable expression of cytokeratins. Diagnosis of the tumor includes endoscopic examination of the nasal cavity and nasopharynx, magnetic resonance imaging (MRI) and computed tomography (CT) of the skull base, paranasal sinuses with intravenous contrast. PET-CT is advisable to use for the detection of regional and distant metastases, as well as for suspected relapse. In patients of adult age, a negative effect on the outcome of the disease was detected, the detection of metastases in the lymph nodes of the neck, the presence of tumor cells at the edges of tumor resection and a high degree of malignancy of the tumor according to the Hyams system. Therapeutic approaches depend on the stage of esthesioneuroblastoma by Kadish. In the A-stage, surgical treatment is advisable. In the presence of tumor cells at the edges of the resection or residual tumor, radiation therapy is performed. In case of B-stage, surgical treatment is combined with the mandatory irradiation of the primary tumor area. In patients with the C-stage, neoadjuvant chemotherapy or radiation is performed, followed by a surgical treatment, adjuvant chemotherapy and/or radiation therapy. Patients with D-stage chemoradiation therapy is indicated. There is no consensus on an effective drug regimen. Overall 5-year survival varies significantly depending on the design of the study — 55% to 98%. Further study of the features of the clinical picture, morphological and molecular features and the course of the disease will help to improve our understanding of the nature of the tumor.

Introduction. Esthesioneuroblastoma is a rare neuroectodermal malignant tumor. The incidence of this tumor in children under 15 years of age is 0.1 per 100,000 pediatric population. The information on incidence, disease course, and treatment of esthesioneuroblastoma in children vary significantly and depend on the follow-up period and statistical methods.Objective – to assess risk factors for esthesioneuroblastoma and evaluate treatment strategies used in children and their prospects.Materials and methods. This study included 29 patients aged 2 to 17 years diagnosed with esthesioneuroblastoma and treated at the Research Institute of Oncology and Hematology, N.N. Blokhin Russian Cancer Research Center, Ministry of Health of Russia between 1969 and 2019. The median age upon diagnosis was 10 years. Six patients (20 %) developed the disease early in their life (being under 3 years of age). Esthesioneuroblastoma was equally common in boys and girls. More than half of the patients (n = 15; 51 %) had stage IV disease. The primary tumor invaded the maxillary sinus (n = 25; 86 %), orbit (n = 10; 34 %), ethmoid sinus (n = 18; 62 %), and cranial cavity (n = 12; 41 %). The majority of children (n = 28; 96 %) received pharmacotherapy and radiotherapy (n = 27; 93 %); the total focal dose was 50 Gy in case of primary tumor. The affected cervical lymph nodes were irradiated in 10 (35 %) patients (total focal dose 40 Gy). Ten (35 %) patients have undergone surgery.Results. The follow-up period varied between 3 months and 50 years. Nine (34 %) patients are still alive. Fourteen patients (48 %) died due to tumor progression; 1 (3 %) patient died due to complications from special treatment. Five (17 %) patients were lost to follow-up at different stages.Conclusion. The following risk factors were associated with poor prognosis in children with esthesioneuroblastoma: disease onset in early childhood, no adequate diagnosis of distant metastases prior to specific treatment initiation, disseminated disease, and high Ki-67 index. In patients with advanced cancer, surgeries were effective only in combination with chemoradiotherapy. Long-term treatment outcomes in children with esthesioneuroblastoma are poor due to high risk of recurrence and tumor dissemination.

Malignant tumors of parameningeal localization are various morphological neoplasms located in the nasal cavity, nasopharynx, paranasal sinuses and middle ear. As a result of tumor growth, conditions are created for the development of chronic inflammation. Studies of the microbiome of the upper respiratory tract in children with malignant tumors were practically not conducted. Objective of the research: to identify changes in the microbiome of the nasal cavity in children with malignant tumors of parameningeal localization during chemoradiotherapy. Materials and methods: the study included 29 patients with parameningeal tumors, 2–17 years old. Among the included in the study there were 18 boys (62%) and 11 girls (37%). Morphologically, the following were verified: embryonic rhabdomyosarcoma (ERMS) – 17 (58%), alveolar rhabdomyosarcoma (arms) – 3 (10%), other sarcomas – 4 (13%), nasopharyngeal cancer – 5 (17%). All patients received induction chemotherapy. Simultaneous radiotherapy (LT) and chemotherapy (CT) – in 24 (82%) cases. After completing the chemoradiotherapy stage, consolidation therapy continued in 20 (70%) patients. Results: before the start of LT (after the induction stage of chemotherapy), a variety of microflora was observed in the nasal secretions, gram-positive and gram-negative bacteria were isolated in an equal ratio. The absence of growth of microorganisms was determined in 4 (13%) cases before the start of LT. Methicillin-resistant Staphylococcus epidermidis and Staphylococcus haemolyticus were more frequently detected after LT. Colonization of the nasal cavity of Candida albicans occurred before the start of LT in 4 (13%) and persisted after irradiation in 5 (17%) patients. In the delayed period, there was an increase in the percentage of patients who ridiculed gram-negative microorganisms – Pseudomonas aeruginosa in 4 (13%) cases. After 12 months, 3 (10%) patients showed a return of nosocomial flora (S. epidermidis MRSE and S. haemolyticus MRS), a decrease in colonization of P. aeruginosa and the preservation of C. albicans. Conclusion: at different stages of chemoradiotherapy, the nasal mucosa is colonized by various microorganisms that differ in their properties and pathogenicity. The continuation of this study will clarify the clinical significance of certain types of opportunistic microorganisms in the pathogenesis of inflammatory diseases of the upper respiratory tract in children with malignant tumors.

Introduction. Soft tissue tumors account for up to 8 % of all malignant neoplasms in children. According to the international histological classification, about 150 different morphological variants of soft tissue tumors have been registered, of which 45 % are rhabdomyosarcoma (RMS). Most often, RMS occurs in early childhood – the average age of patients at the time of diagnosis is 5 years. The incidence rate of RMS is 0.9 per 100,000 children. In 25 % cases, the initial diagnosis reveals distant metastasis to the lungs, bones, bone marrow, and 8 % – leptomeningeal metastasis. More than 7 % of patients with localized parameningeal RMS develop leptomeningeal metastasis, according to the Rhabdomyosarcoma Study Group.   Purpose of the study – report the incidence, prognosis of leptomeningeal metastasis and treatment outcomes in children with intracranial spread of RMS.   Materials and methods. The study included 45 patients aged 1 to 17 years with a diagnosis of RMS of parameningeal localization with intracranial spread, who received special treatment from 2003 to 2020. The study included 6 (20 %) patients in whom the tumor developed in early childhood (up to 3 years). The boys predominated – 25 (55.5 %) in the study. The primary tumor spread to the orbit in 7 (15 %) cases, the skull base in 7 (15 %) cases, the middle ear in 4 (8 %) cases, the nasopharynx in 3 (6 %) cases, and the brain substance was affected in 16 (35 %). Metastases in regional lymph nodes were determined in 7 (15 %) patients. Multiple metastatic lesions of bones and bone marrow – 4 (9 %) cases, leptomeningeal metastases – in 2 (4 %). 45 (100 %) patients received drug treatment according to the protocols approved by the Academic Council of the Research Institute of Pediatric Oncology and Hematology at N. N. Blokhin National Medical Research Centerof Oncology, Ministry of Health of Russia. Radiation therapy was performed in 33 (74 %) patients, while total focal dose of 50 Gy was administered to the primary tumor. Affected lymph nodes of the neck were irradiated in 10 (23 %) patients, total focal dose is 45.0 Gy. Surgical treatment was performed in 15 (34 %) patients. Multicomponent treatment was performed in 15 (34 %) patients.   Results. During the observation period from 12 months to 14 years, 21 (49 %) patients are alive. 21 (51 %) patients died from tumor progression, 1 (2 %) died from complications of special treatment.   Conclusions. The treatment of this group of patients is one of the urgent problems of pediatric oncology, which is based on polychemotherapy, supplemented by intrathecal administration of anticancer drugs and craniospinal irradiation. The development of new therapies requires a multidisciplinary approach to achieve a significant improvement in the survival of children with leptomeningeal metastases RMS of parameningeal localization.

Relevance. Retinoblastoma (RB) is the most common primary intraocular tumor in children. The incidence of RB ranges from 1:14,000 to 1:20,000 newborns. To date, the survival rates of patients with RB reach almost 100 % with timely and adequate diagnosis. Among childhood oncological diseases, RB accounts for 2.3–4.5 % and 85–90 % among intraocular tumors in children. According to the volume of tumor spread, intra- and extraocular forms of the disease are distinguished. Extraocular RB is the spread of the tumor beyond the eye with invasion of the orbital tissues, as well as the possible involvement of adjacent areas, including intracranial without and with regional and/or remote metastases. The main method of treatment of children with extraocular RB is neoadjuvant chemotherapy (CT) with planning of surgical intervention and adjuvant therapy. High-dose CT (HDCT) with autologous hematopoietic stem cell transplantation (auto-HSCT), it allows to increase relapse-free survival in patients without metastatic lesions of the brain and spinal cord, but with their defeat, the prognosis of survival is extremely unfavorable, the nature of the disease is recurrent with 100 % lethality.Description of the clinical case. We report a case of bilateral RB: OD – with extraocular and intracranial spread of the tumor along the optic nerve with a lesion of the chiasm and a transition to the initial parts of the visual tracts. Secondary glaucoma. OS – with intraocular tumor growth in a 3-year-old child. After neoadjuvant chemotherapy, including intrathecal, a simultaneous two-stage operation was performed in the volume of bone-plastic (temporo-orbito-zygomatic) pterionic craniotomy on the right with prechiasmal resection of the right optic nerve and enucleation of the right eye. In the postoperative period, adjuvant chemotherapy was performed, followed by HDCT with auto-HSCT. Radiation therapy has become the final stage of treatment. Brachytherapy for OS tumor and remote radiotherapy for craniospinal region, right orbit, optic nerve stump with chiasm and pituitary pedicle were successively performed. After 14 months from the beginning of treatment and 5 months after its completion, a leptomeningeal relapse of the disease was detected.Conclusion. Rare observations of RB with damage to the visual tracts do not allow us to sufficiently study the features of the course of the tumor process, as well as to develop a single effective approach to antitumor treatment. Among the causes of mortality in patients with extraocular RB, the main one is metastasis, metastasis in the brain and spinal cord.