For giant mediastinal teratomas, the only treatment option available is usually open-chest surgery, which causes significant trauma, leads to obvious postoperative pain and may result in long-term complications such as chest wall deformity. Currently, we have developed a new treatment method. We use a double retractor system to pull the upper and lower ends of the sternum, lifting it to obtain sufficient surgical space behind the sternum. This enables us to perform minimally invasive tumor resection through the subxiphoid approach with thoracoscopy. The advantages of this method include reduced surgical trauma and postoperative pain, shortened hospital stay, and improved cosmetic effect

Inclusion Criteria:

• Age: 10 - 70 years old, gender unrestricted; Preoperative enhanced CT or MRI confirms anterior mediastinal mass with the maximum diameter ≥ 7 cm; Intraoperative frozen section pathology confirms teratoma (mature or immature type); American Society of Anesthesiologists (ASA) classification grade I - III, with acceptable cardiopulmonary function for single-lung ventilation; No severe thoracic deformity or severe adhesion in the posterior mediastinum (assessed by preoperative imaging); Patients voluntarily sign the informed consent form, understanding the purpose and potential risks of the study.

Exclusion Criteria:

• Tumors invading major blood vessels (such as the innominate vein, superior vena cava, or aorta) or the pericardium require combined vascular/pericardial resection and reconstruction; Tumors crossing the midline and encasing the trachea or esophagus require multidisciplinary joint surgery; Previous mediastinal surgery or radiotherapy history, leading to local anatomical structure disorder; Coagulation dysfunction (INR > 1.5 or platelet count < 50×10⁹/L); Severe immune deficiency (such as HIV infection, long-term glucocorticoid treatment); Pregnant or lactating women; Concurrent other malignant tumors (metastatic lesions need to be excluded); Severe cardiopulmonary diseases (such as COPD GOLD Ⅲ-Ⅳ grade, NYHA cardiac function Ⅲ-Ⅳ grade); Mental illness or cognitive impairment that cannot cooperate with postoperative follow-up; Participated in other clinical trials that may interfere with the results of this study.