Thymoma is the most common anterior mediastinal tumor, with a few cases located in the posterior mediastinum or other parts of the chest. It has the third highest incidence among mediastinal tumors. According to the histological structure, thymoma can be divided into three types: 1) lymphocytic thymoma containing 80% or more lymphocytes; 2) epithelial thymoma containing 80% or more spindle-shaped epithelial cells; 3) mixed type, that is, lymphoepithelial type. Most thymomas are benign, commonly found in adults, and are often clinically asymptomatic and only found incidentally during routine chest X-ray examinations. Sometimes there is chest tightness, chest pain, cough and shortness of breath. If the thymoma is malignant, the symptoms are obvious and fast-growing, and it is often prone to recurrence after surgical excision. It has been reported in the literature that thymoma can be associated with immunodeficiency states and aplastic anemia, and has a very unusual association with myasthenia gravis. In 1939 Blalocle et al. first reported a case of myasthenia gravis in which symptoms improved after thymectomy. The relationship between the two diseases was later studied by many scholars. The incidence of myasthenia gravis in patients with thymoma is about 20%. In contrast, only 15% of patients with myasthenia gravis have thymoma. The 5-year survival rate decreases when myasthenia gravis occurs in patients with thymoma, while patients with myasthenia gravis with thymoma have a lower remission rate than those with myasthenia gravis without thymoma. x-ray: an anterosuperior mediastinal mass is seen, which is more clearly shown on oblique photographs as a garden-like mass or a tongue-shaped shadow, respectively. They are characterized by upward extending cords extending toward the top of the pleura, which are often confirmed to be related to adhesions and traction during surgery. The relationship between the tumor and the surrounding structures is currently evaluated preoperatively using enhanced CT. As with most mediastinal tumors, the preferred treatment is early surgical resection of the tumor, with satisfactory results in benign cases and complete resection in malignant cases, followed by radiation therapy, even in the presence of pleural metastases or other signs of local invasion. Regarding the choice of surgical incision, it should depend on the size and location of the tumor, and the principle is to fully reveal it. If the tumor is small and extends to one side, thoracoscopic mediastinal tumor resection and debulking is adopted, which can achieve the same effect as open surgery and can reduce trauma; if the tumor is large and located in the middle and posterior mediastinum, a unilateral posterior lateral open incision should be performed; if the tumor is located behind the sternum and protrudes to both sides of the chest, a median sternal incision can be adopted. This kind of longitudinal sternal incision can, on the one hand, conduct a comprehensive exploration of the anterior mediastinum and, on the other hand, completely remove all the thymus and the fatty tissue of the anterior superior mediastinum from the entrance of the thorax to the diaphragm. Based on the surgical findings and histological examination of the surgical specimen, thymoma is generally divided into three stages: ① non-infiltrative stage: the envelope is intact, although the tumor has invaded the envelope, but has not penetrated the envelope; ② infiltrative stage: the tumor has penetrated the envelope and invaded the mediastinal fatty tissue; ③ extended stage: the tumor has invaded the surrounding organs or has metastasis in the chest. The literature reports that the recurrence rate of stage I and II patients is low, accounting for about 4%, while the operative mortality rate of stage III patients is as high as 27%, and the recurrence rate is as high as 38%, and the 5-year survival rate after surgery is about 40%.