Epithelioid Hemangioendothelioma of the Azygos Vein

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Background. Epithelioid hemangioendothelioma (EHE) is a malignant vascular tumor of mesenchymal origin. In the mediastinum, EHE originates from the large venous vessels of the superior vena cava.The purpose of the study was to describe a rare clinical case of EHE of the unpaired vein and analyze literature data to improve diagnosis and treatment of this disease.Case presentation. We present a rare case of EHE of the unpaired vein in a 23-year-old male patient who admitted to the Herzen Moscow Oncology Research Institute with a posterior mediastinal tumor detected in August 2022. It was known from the medical history that the patient had undergone diagnostic right-sided thoracotomy and tumor biopsy at the place of residence. Morphologically, the tumor was an epithelioid hemangioendothelioma. The histological re-assessment of biopsy specimens at the Herzen Moscow Oncology Research Institute confrmed the diagnosis of EHE. Computed tomography of the chest organs revealed a mass in the posterior mediastinum (in the projection of the lumen of the unpaired vein), measuring 16×14×41 mm, with relatively clear even contours, close to the posterior wall of the trachea at the bifurcation level, the posterior wall of the right main bronchus, the left semicircle of the esophagus (without signs of invasion). Based on the data on the presence of a vascular tumor in the posterior mediastinum on the right, a multidisciplinary medical consilium recommended surgical treatment: right thoracotomy, removal of a posterior mediastinal tumor with resection of the azygos vein, marginal resection of the superior vena cava, and thrombectomy from its lumen. The duration of surgery was 180 minutes, blood loss was 200 ml. Morphological examination confrmed EHE of the unpaired vein. No complications were observed in the postoperative period. The patient was discharged from the hospital on the 8th day after surgery in a satisfactory condition.Conclusion. EHE of the unpaired vein is an extremely rare vascular tumor. The clinical feature of EHE of the unpaired vein is the absence of any pathognomonic signs, which complicates differential diagnosis of mediastinal tumors. Surgery is currently the optimal treatment approach.