Introduction. Computer modeling and additive technologies are increasingly used in medicine. Oncoorthopedics is no exception. Careful preoperative planning and the creation of individual instruments make it possible to perform radical operations, which allows maximum preservation of healthy tissues and leads to an increase in the functional potential of patients in the postoperative period.
Objective – to improve the results of surgical treatment of patients with malignant bone tumors of complex anatomical localizations using computer modeling and additive technologies.
Materials and methods. This study included 44 patients (26 men and 18 women) with malignant bone tumors. The mean age of the patients was 39 ± 15.57 years (range 14 to 66 years). In 39 cases, the anatomical location of PSI application was the pelvis, in four cases it was the distal femur, and in one case the femoral shaft. The most common histological type of tumor was chondrosarcoma (47.7 %).
Results. In the case of primary resection of the pelvic bone tumor (26 patients), according to the histological examination, radical resection margins (R0) were observed in 25 cases. In one case, after removal of the tumor, a discrepancy between the preoperative histological conclusion (G2 chondrosarcoma) and postoperative (dedifferentiated G3 chondrosarcoma) was revealed. During operations to remove tumors of the distal segment of the femur and resection of the tumor of the diaphysis of the femur, in all cases, the radicality was R0.
Conclusion. Individual navigation devices have proven themselves in clinical practice. The results obtained in our study demonstrate their effectiveness in the treatment of malignant bone tumors.

Lymphangiosarcoma is a rare and aggressive malignancy. It is always associated with chronic lymphedema. This disease was described in 1948 by F.W. Stewart and N. Treves in 6 patients undergoing mastectomy. The incidence of lymphangiosarcoma is varied from 0.07 to 0.45 %. Average time of developing lymphangiosarcoma after mastectomy is 10.3 years. The etiology of this malignant tumor remains uncertain. Histologically LAS arises from epithelial cells of lymphatic vessels in the area of chronic lymphedema. There is no standard treatment of lymphangiosarcoma. Radiation therapy and chemotherapy do not significantly improve the survival rate. At the moment, wide local excision and amputation offer the best chance for long-term survival. Unfortunately, the prognosis remains poor.
The study objective – is to draw attention to lymphangiosarcoma and to show the importance of its prevention.

During tumor growth, one of the leading functions in providing oxygen and nutrients to the neoplasm belongs to the system of its angiogenesis. Vascular endothelial growth factor (VEGF) is a major inducer of angiogenesis and appears to be a key modulator of the antitumor response. Indeed, VEGF modulates the innate and adaptive immune response through direct interaction with the tumor and indirectly through modulation of protein expression on endothelial cells or vascular permeability. This review provides the main characteristics of the VEGF family, ligands and their receptors. The role of VEGF in the pathogenesis of soft tissue sarcomas and their relapses is discussed, and possible therapeutic approaches in the treatment of these tumors, directed at the VEGF system, are considered.

Introduction. Oncological endoprosthesis for tumors of the pelvic bones is rare. It is associated with certain difficulties and is insufficiently investigated.
The study objective is to evaluate the results of surgical treatment of patients with tumors of the pelvis performed between 2012 and 2021 at the N.N. Petrov National Medical Research Center of Oncology, Ministry of Health of Russia.
Materials and methods. The study included 23 patients with primary and secondary tumors of the pelvic bones who underwent limb-saving surgeries with substitution of the postresection defect with an endoprosthesis between 2012 and 2021. Mean follow-up duration was 19 months.
Results. The most common postoperative complication was infection of the postoperative wound (n = 8; 35 %). Mechanical complications associated with the installed metallic prosthesis were observed in 4 (17 %) patients. Function al results were evaluated after 6 months using the Musculoskeletal Tumor Society Score (MSTS). Mean score per this scale was 53 % which corresponds to satisfactory outcome.
Conclusion. Patients with malignant tumors of the pelvic bones should undergo treatment only in specialized medical facilities. Patients for organ-saving therapy should be carefully selected.

Introduction. An additional or the only way to treat tumors of the chest wall is often a surgical method, which inevitably results in a post-resection defect. Reconstruction of extensive chest wall defects remains an unsolved problem for surgeons around the world.
The study objective – to present the long-term oncological and functional results of treatment of a patient with multiple locally recurrent leiomyosarcoma after reconstruction of an extensive post-resection chest wall defect using superelastic 3D frame modules made of titanium nickelide. Reconstruction of the chest wall with 3D modules after extensive block resection showed the possibility of not only restoring the anatomy in the area of the post-resection defect, but also maintaining the biomechanics of breathing in the postoperative period.
Clinical observation. This study presents a clinical case of extensive resection and successful one-stage reconstruction of the chest wall skeleton with 3D superelastic titanium nickelide modules in a patient with recurrent leiomyoma with locally recurrent leiomyosarcoma.
Results. The superelastic modules did not limit the width of the resection during the operation and ensured long-term stability of the position of the reinforcing elements of the artificial framework. Control examinations showed no tumor recurrence after 12 months and maintaining patient performance.
Conclusion. The effectiveness of the proposed reconstruction expands the possibilities of treating patients with tumors of the chest wall.

Chondrosarcoma is one of the most common tumors in adults. Resectable chondrosarcomas requires surgical treatment, and tend to local recurrence, often repeatedly.
A case report of a 38 years old female patient with secondary chondrosarcoma of femur is presented. The role of multidisciplinary team in tactic choice of primary treatment and recurrence treatment is shown.