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: Histiocytosis is a heterogeneous group of rare diseases of unknown etiology. LCH is characterized by an abnormal proliferation of histiocytes (activated dendric cells and macrophages). Langerhans cell histiocytosis (LCH) is the most common form of histiocytosis, it is a potentially fatal diseases. Early detection of LCH plays an important role in its prognosis and outcome. However, the role of advanced methods of nuclear medicine in diagnosis of LCH is still to be researched. We have long-term experience in observing pediatric patients with LCH. Taking into the account the difficulty of diagnostic task for bone scintigraphy in identifying lytic bone destruction, we stated the following objective of the study.

Purpose: Retrospective and prospective analysis of bone scintigraphy examinations of treatment-naive pediatric patients with LCH and calculate the diagnostic efficacy of bone scintigraphy. Material and methods: We analyzed 60 examinations of treatment-naive pediatric patients with proven case of LCH (2014-2019). The scanning was performed using whole body mode, 3 hours after intravenous injection of bone-seeking radiopharmaceutical 99mTc-MDP on Symbia E, T2 (Siemens, Germany). The median age was 5.6 years.

Results: During examination we visualized 88 lesions with pathological level of accumulation of radiopharmaceutical in 60 patients. 84 with high level of accumulation (>120 %); 3 with slightly increased level of accumulation (100–120 %) and 1 with lower than normal level of accumulation (<100 %). The median level of accumulation of radiopharmaceutical was 268 %. Max level of accumulation was 1422 % (patient with subtotal involvement of femoral bone). Min — 60 % (patient with lytic destruction in orbital bone). During X-Ray we found out 97 pathological focuses of bone lytic destruction. In 3 patients with polyostotic form we found extra focuses on scintigraphy, which were confirmed with following examination and X-Ray. 8 lesions were not found on scintigraphy in 8 patients.

Сonclusions: We evaluated diagnostic accuracy of bone scintigraphy with 99mTc-MDP in treatment-naïve pediatric patients with proven case of LCH. Sensitivity, specificity, NPV and PPV — 91.6, 50.0, 11.1, 98.6 %, respectively.

The functional optimization of the composition of radiopharmaceutical pairs based on the prostatespecific membrane antigen (PSMA) for the radionuclide theranostics of castration-resistant prostate cancer was carried out. The analysis of radiation-physical and dosimetric characteristics of 9 radionuclides for diagnostic components of theranostic pairs and 6 radionuclides for therapeutic components is carried out. It was shown that positron-emitting radionuclides 18F and 68Ga should be considered optimal for the diagnosis and monitoring of the effectiveness of theranostics, and 177Lu beta-emitting radionuclide and 225Ac alphabeta-emitting radionuclide should be considered as the radionuclide therapy. The values of the total and organ radiation risks of secondary radiation-induced cancers in patients who have completed several courses of theranostics are calculated. It is shown that for 2 teranostic pairs based on 177Lu‑PSMA the radiation risk is higher than significant, while for 2 teranostic pairs based on 225Ac the risk falls within the range of a significant level. The calculated radiological criteria for discharge of patients after a course of theranostics from nuclear medicine departments show the fundamental possibility of performing an outpatient treatment regimen using any of the 4 considered theranostic pairs.

Iatrogenic intraoperative ureter injuries are rare complications in medical practice that can threaten to a patient ‘s life. There are no standardized approaches in the treatment of this condition. This work presents the experience of our clinic of non-standard mini-invasive treatment of patients with the use of Rendez-vous technique, which allowed to restore the integrity of the upper urinary tract and natural passage of urine without repeated surgery.

Introduction: Esophageal cancer (EC) is a malignant disease with low survival rates and limited treatment options in the later stages. The epidemiological situation in developed countries tends to improve. However, in most states, including the Russian Federation, the situation remains in critical condition.

Epidemiology of EC: Esophageal cancer is one of the most aggressive malignant disease. According to the International Agency for Research on Cancer (IARC), in 2018, 572 thousand new cases of RP were registered in the world (3.2 % of the total number of malignant disease). In 2018, 508.6 thousand deaths from cancer were recorded in the world (5.3 % of the total number of deaths from cancer, 6th place) [1].

EC risk factors: The following factors play an important role in the etiology of squamous EC:

1. Diet (nitrites, hot food and drinks, insufficient intake of vitamins and minerals with food).

2. Tobacco and alcohol use are independent risk factors, but when combined with others, they increase

the risk of the disease.

3. Achalasia of the cardia.

4. Burns of the esophagus.

5. Autosomal dominant diseases characterized by hyperkeratosis of the palms of the hands and feet.

The risk of developing EC reaches 37 % [2].

6. Human papillomavirus types 16 and 18 causes a risk of EC in 37 % of patients.

Diagnostic methods: Traditional methods for the diagnosis of EC are: esophagogastroduodenosocpy with biopsy, endoscopic ultrasound with puncture biopsy of the mediastinal lymph nodes, computed tomography of the chest and abdominal organs (including contrast), magnetic resonance imaging of the chest cavity (including with contrasting), positron emission tomography with 18F-fluorodeoxyglucose (including combined with computed tomography).

Case report of adrenocortical carcinoma recurrence after adrenalectomy and combined treatment.

We report the case of a 46 year old man with silent adrenal mass. Imaging showed a large left adrenal mass with no evidence of distant metastasis. Complete surgical excision of the tumor was performed. After 5 years after surgical treatment, a local relapse of the disease was detected according to the results of CT, followed by PET/ CT with 18F-FDG — no evidence of distant metastases were detected. After complex treatment metastases were diagnosed by follow up PET/CT.

This case report demonstrates possibilities of PET/CT with 18F-FDG in determination of adrenal mass malignancy and in cases of recurrent adrenocortical cancer, in cases of metastatic lesions.

Purpose: To demonstrate the capabilities of a complex of multiparametric ultrasound and MRI with intravenous contrast in the detection and characterization of atypical hepatocellular carcinoma with the example of a clinical case of a middle-aged patient without liver cirrhosis.

Material and methods: Comprehensive study of medical history, outpatient records, results of clinical, laboratory, instrumental and morphological methods with independent retrospective analysis of the histological preparation of focal liver lesion.

Results: Diagnostic search data are presented in a 48-year-old patient with hepatocellular carcinoma without signs of liver cirrhosis. The diagnosis required 1.5 months of examination in gastroenterological department, repeated review of the histological preparation by morphologists. The disease debuted with weakness after physical exertion, which was noted during a planned multiparameter abdomen ultrasound examination. During the study, multiple focal formations with uneven fuzzy contours, an inhomogeneous structure were visualized. Stiffness of the parenchyma in focal liver lesion is 108.29 kPa due to 2D-SWE. Further tactics consisted of hospitalization with further laboratory examination and abdomen MRI with intravenous contrast enhancement. Considering the results of instrumental examination, the patient was prescribed a puncture aspiration biopsy of focal liver lesion under ultrasound control followed by morphological verification.

Conclusion: The presented clinical observation demonstrates the need of use an integrated approach in instrumental imaging methods in the diagnosis of atypical hepatocellular carcinoma.