The main method of treating rare mesenchymal tumors PEComas is surgical removal of the tumor and external-beam radiation therapy has historically been considered ineffective. However, the individual cases in the foreign literature as well as this article authors’ experience in the form of the clinical case provided in it shows the possibility of achieving some anti-tumor effect due to the use of aggressive variants of radiation therapy. The use of variations of stereotactic radiotherapy with high dose per fraction and sum dose as an neoadjuvant and definitive treatment looks promising.

Introduction. Giant cell tumor of bone is a relatively rare, locally aggressive osteolytic skeletal neoplasm with uncertain behavior: recurrence rates up to 70 % and distant metastases occur 2–6 % of cases. Nowadays denosumab is the choice of therapy for patients  with unresectable  or advanced disease. However,  the efficiency,  duration or administration and most of all safety of continuous denosumab are not established.Materials and methods.  Fourty advanced or unresectable giant cell tumor cases were observed from 2005 till 2020 in N.N. Blokhin National Medical Research Center of Oncology. The average age of pts was 33,6 ± 13,1 years (18–64), and the women and men ratio was about 2,1 : 1. The most commonly affected sites were long bones of the lower extremities (22,5 %), sacrum (22,5 %), long bones of the upper extremities (17,5 %), spine (17,5 %), pelvis (10 %) and others. 70 % of cases were anatomically compounded due to tumor localization and 27,5 % of cases were primary disease. 37,5 % of cases were with pulmonary metastases. Patients underwent computed tomography / magnetic resonance imaging every 3 months during the first three years and then once every six months. Patient received subcutaneous denosumab 120 mg every 4 weeks with a loading dose of 120 mg subcutaneous on study days 8 and 15. After 2 years monthly therapy and confirmed stabilization  effect patient  then  received maintenance  therapy: once in three  months injection. All patients received daily calcium and vitamin D supplement.Results. Median follow-up was 52,8 ± 41,3 months (3–219 months). The average denosumab injections were 25 ± 16 (4–85). Clinical and radiographically stabilization of the effect occurred on average at 12 ± 8 (4–32) injections. Hypocalcemia was registered in one case (2.5 %). There was significant improvement of Karnofsky scale, Visual analogue scale (VAS) and Watkins scale (p <0.001). 5-year progression-free survival for was 70.1 % (95 % confidence interval 55.7–88.0), the median was not reached. Progression of disease was observed only in subgroup with violations in denosumab administration or its cancellation (32,5 %). 3-year progression-free survival in subgroup with violations in denosumab administration or its cancellation was 10 % (95 % confidence interval 15.5–64.1). In subgroup with continuous denosumab and once in three months injection after 2 years monthly therapy there was no signs of progression.Conclusions. In this study we showed evidence of safety and effectiveness of continuous denosumab for unresectable or advanced giant cell tumor even with once in three months injection therapy. Denosumab for advanced giant cell tumor of bone became a choice of treatment, but we need further investigation for observation long term denosumab effectiveness and complications.

Background. The standard treatment for giant-cell tumors of the bone includes radical surgery. However, specific anatomical location of the tumor and/or its spread may hinder its complete excision or result in poor functional outcomes. Currently, combination treatment that includes preoperative denosumab and surgery is preferable. It saves patients’ lives and improves their quality of life. Reduction of local recurrence rate by combination therapy for giant-cell tumors of the bone is being actively studied now.Objective – to analyze treatment outcomes of patients with giant-cell tumors of the bone, including those who received combination treatment that included preoperative therapy with denosumab followed by surgery.Materials and methods. This study included 277 patients with giant-cell tumors treated in N.N. Blokhin National Cancer Research Center between 2005 and 2020. The mean duration of follow-up was 56 months. Study participants were divided into two groups. Group 1 included patients who received surgical treatment alone (n = 212), whereas Group 2 comprised patients who received combination treatment (n = 65). Neoadjuvant therapy included subcutaneous denosumab 120 mg on days 1, 8, 15, and 28, then every 4 weeks until stable effect. There were two variants of surgical treatment: radical (removal by a single block or segmental resection with defect replacement, with or without fixation) and non-radical (excochleation or marginal resection with defect replacement, with or without fixation).Results. During treatment, patients in Group 2 had a significantly milder pain syndrome (assessed both using the visual analog scale for pain and Watkins scale) compared to Group 1. In case of radical surgery, the incidence of local recurrence was 12 % and 0 % in Groups 1 and 2, respectively; the difference was significant (р <0.05). Tumor location and volume of surgery played an important role in disease recurrence (р <0.05). The incidence of complications after radical surgery was 36.9 % and 12.5 % in Groups 1 and 2, respectively; the difference was significant (р <0.05). In addition to that, neoadjuvant therapy with denosumab substantially reduced the duration of surgery and blood loss in patients with challenging anatomical location of the tumor (р <0.05).Conclusion. Combination treatment for giant-cell tumors that includes neoadjuvant therapy with denosumab reduces the risk of recurrence, duration of surgery, blood loss, and the risk of postoperative complications. However, it is important to consider tumor location and the volume of surgery. Since the disease is quite rare, further study of long-term efficacy and safety of combination treatment for giant-cell tumors, including rare ones and those with challenging anatomical location, is necessary.

Chordomas of the sacrococcygeal region account for more than 50 % of all sacral tumors. These malignant neoplasms grow slowly and are asymptomatic for a long time. As a result, chordomas often reach large sizes and affect the neurovascular structures of the sacrum and pelvic organs. The use ofen-bloc resection allows to increase survival rates and reduce the risk of progression. However, this method of chord treatment is difficult for surgeons and in most cases, after surgery, the quality of life of patients decreases. The improvement of imaging methods, the success of oncological orthopedics and radiation therapy allow performing radical organ-preserving operations. In this article, we will consider the modern concept of treatment with a sacrococcygeal chord.

Primary synovial chondromatosis is well known in large joints, the knee, followed by hip mainly in male adults are the most commonly involved sites. Primary process represents benign neoplastic formation of hyaline cartilage nodules in the subsynovial tissue of a joint, tendon sheath, or bursa. Interesting developmental progress may be seen; the nodules may detach from the synovium and form loose bodies. The differential list of the synovial chondromatosis includes benign and malignant conditions. The pathologic appearance may simulate chondrosarcoma because of significant histologic atypia. Radiologic correlation is vital for correct diagnosis. There are only limited publications about synovial chondromatosis of the spine, published in English literature and absolutely no published data in Russian literature. Treatment of primary disease is surgical synovectomy with removal of chondral fragments. The recurrence rates range significantly. This is the first case of the primary synovial chondromatosis of the spine in our practice.

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Introduction. Chordomas are rare malignant neoplasms that are highly recurrent and with limited treatment options. Invasion of the vital structures of the nervous system complicates their treatment. The search for new methods of drug therapy for chordomas is an urgent problem. The aim of the research was to study PD-L1 expression in tumor cells and tumor infiltrating lymphocytes (TILs) in chordoma samples and its interrelation with tumor characteristics and prognosis. Materials and methods. We analyzed PD-L1 expression in 30 primary chordomas using immunohistochemistry and differences in independent groups using Chi-square and Kruskal–Wallis tests. Survival analysis was performed by constructing Kaplan–Meier survival curves. We compared the significance of differences with the logarithmic rank test. Differences were considered significant at p<0.05. Results. PD-L1 expression was detected in tumor cells in 43% of samples and in TILs in 80%. PD-L1 expres-sion in tumor cells and TILs was not associated with the clinical features of the disease. However, PD-L1 expression in tumor cells in all samples correlates positively with the content of this marker in TILs (r=0.409, p=0.028). Different histological variants of chordomas were shown to differ in the content of PD-L1 in both tumor cells and TILs. PD-L1 expression in tumor cells is not a predictor of the disease, while its expression in TILs tends to be a marker of a favorable prognosis (HR=0.1429; p=0.0570). Conclusion. We found the lowest level of PD-L1 expression in both tumor cells and TILs in dedifferentiated chordoma. PD-L1 expression in TILs is associated with a favorable prognosis of chordomas and indicates the potential for the use of checkpoint inhibitors in therapy. Keywords: chordoma, PD-L1, lymphocytes, prognosis, survival

Soft tissue sarcomas of the hand and foot comprise a rare subgroup of mesenchymal tumors with more favorable oncological prognosis. For this type of tumors, several options of surgical treatment exist depending on histological subtype, size and local tumor advancement. Additionally, due to significant functional load on the distal parts of the limbs, surgical techniques for treatment of these patients have specific characteristics. However, publications on progression characteristics and prognosis of soft tissue sarcomas of the hand and foot are lacking.This review describes soft tissue sarcomas of the hand and foot and analyzes surgical techniques for treatment of patients with this type of tumor.