The most common thymic tumor is thymoma, accounting for about 90% of cases, followed by thymic carcinoma, accounting for about 5% of cases. Thymoma is a common anterior superior mediastinal tumor derived from thymic epithelium and is closely related to myasthenia gravis. It is difficult to determine the benignity and malignancy based on histological pattern alone, but must be combined with clinical features such as invasion and metastasis. Clinical presentation 1/3 of patients with thymic malignancy present with asymptomatic anterior mediastinal masses, 1/3 present with local symptoms, and 1/3 present with paraneoplastic syndrome. Metastases are uncommon in patients with thymoma at the time of presentation, as opposed to thymic carcinoma. Diagnosis CT-guided core needle biopsy is the first choice to confirm the diagnosis of mediastinal masses. Pathology The most widely used pathologic classification system for thymic tumors is the WHO histologic staging criteria for thymus developed in 1999, which is an independent prognostic factor after surgical resection. WHO histologic staging criteria for thymic epithelial tumors: A thymoma (medullary or spindle cell thymoma); AB thymoma (mixed type); B1 thymoma (i.e., lymphocyte-rich thymoma, lymphocytic thymoma, cortical-dominant thymoma, or organoid thymoma); B2 thymoma (cortical type); B3 thymoma (i.e., epithelial, atypical, squamous-epithelioid thymoma or well-differentiated thymic carcinoma); and type C thymoma (thymic carcinoma). The most widely used staging method is Masaoka staging, which is the most important prognostic factor for thymoma. stage: pleural or pericardial dissemination; clinical stage IVb: lymphatic or hematologic metastasis. Treatment options: Both thymoma and thymic carcinoma are rare diseases, and most of the current studies on their treatment options are retrospective. 1. Surgery Surgery is the most effective treatment for thymic tumors and has an important role in stage I tumors, stage II-III locally aggressive thymomas and recurrent disease. For resectable anterior mediastinal thymoma, surgical resection should be performed immediately. Complete surgical resection is the most important factor for cure. Surgery alone is not the most effective treatment for patients with stage IVa thymoma, and multidisciplinary comprehensive treatment should be performed. 2.Radiotherapy Thymoma is sensitive to radiotherapy. Radiotherapy plays an important role in the treatment of thymoma, including postoperative adjuvant therapy and treatment of locally advanced, unresectable and recurrent disease. Radiotherapy is not required after complete resection of stage I thymoma. There has been controversy as to whether stage II patients should be routinely treated with radiotherapy after surgery, but a growing number of studies have confirmed that patients with completely resected stage II thymomas do not benefit from radiotherapy. Stage III and IV thymomas and thymic carcinomas have a high recurrence rate after surgery and should be treated with radiotherapy after surgery to control local recurrence. The tumor stage is the main basis for deciding whether to administer radiotherapy after surgery, but the WHO classification of the tumor should also be considered. The recommended dose of postoperative radiotherapy is 45-55 Gy, and for postoperative residual lesions, the dose can be 60 Gy. 3D conformal radiotherapy or intensity modulated radiotherapy can be used, but prophylactic supraclavicular lymph node radiotherapy is not recommended. (Intensity modulated radiation therapy (IMRT) is a kind of three-dimensional conformal radiotherapy, which requires the dose intensity in the radiation field to be adjusted according to certain requirements, referred to as intensity modulated radiotherapy. It is under the condition that the radiation field at each place is consistent with the shape of the target area, the beam intensity is adjusted according to the three-dimensional shape of the target area and the specific anatomical relationship between the vital organs and the target area, and the dose distribution within a single radiation field is not uniform, but the dose distribution within the whole target volume is more uniform than that of three-dimensional conformal therapy). Chemotherapy Chemotherapy can be applied in the palliative treatment of advanced thymic tumors, neoadjuvant chemotherapy and treatment of recurrent disease. When combined with radiotherapy, the method is sequential radiotherapy to avoid the accumulation of treatment side effects. Chemotherapy for invasive thymoma has achieved significant efficacy in the last decade or so. Some scholars have reported in recent years that preoperative and postoperative chemotherapy improves the efficacy of stage II and above invasive thymoma, and increases the surgical resection rate and reduces the recurrence rate. There are single agent chemotherapy and combination chemotherapy for invasive thymoma, and there are two types of combination chemotherapy: platinum-free and platinum-containing. Most scholars recommend platinum-based combination chemotherapy. Thymoma is relatively sensitive to chemotherapy, and the current standard regimen is based on the combination of cisplatin and anthracyclines, including PAC (cisplatin + doxorubicin + cyclophosphamide), ADOC (cisplatin + doxorubicin + vincristine + cyclophosphamide), PE (cisplatin + etoposide), VIP (isocyclophosphamide + etoposide + cisplatin), etc. 4.Targeted therapy Several studies in recent years have shown that epidermal growth factor receptor (EGFR) and c-KIT mutations are rare in thymoma and thymic carcinoma. Thymoma mostly expresses EGFR but rarely expresses c-KIT, while thymic carcinoma is the opposite. While the results of targeted drug therapy are disappointing, the efficiency of gefitinib and erlotinib is in the range of 1%-4%, and imatinib seems to be ineffective in thymic carcinoma, which indicates that there may be other gene activating mutations in thymic tumors, and targeted therapy and predictive factors have to be explored. 5. Treatment of recurrent disease The most common site of recurrence of thymoma is the thorax, followed by the mediastinum. For patients with recurrence, surgery is still the main treatment, and for those who cannot be operated, radiotherapy is an effective method. There are also reports in the literature that paclitaxel, docetaxel and gemcitabine have been shown to be effective. Prognostic factors Masaoka staging, WHO classification, complete resection and tumor size are important prognostic factors. Early recurrence (<40 months) is a poor prognostic factor