Thymoma is one of the most common primary tumors of the anterior mediastinum and is a group of diseases with distinctive clinicopathological features and multiple paraneoplastic symptoms originating from different thymic epithelial cells. The vast majority of thymomas are located in the thymic region of the anterosuperior mediastinum, while a very small number may occur ectopically in the posterior mediastinum, lower neck, perihilar region, pleura, or lung parenchyma. Smaller thymomas may be asymptomatic. When the tumor grows to a certain size, it will produce symptoms of compression and irritation of surrounding tissues such as chest pain, chest tightness, cough and anterior chest discomfort. Mediastinal masses can be detected by chest X-ray, chest X-ray or chest CT examination. When the tumor presses on the veins or superior vena cava, it may produce corresponding obstruction. Benign thymoma grows slowly, but if symptoms worsen rapidly in short term, severe irritating cough, pleural effusion, pericardial effusion, and peripheral skeletal pain, all indicate the possibility of aggression. Thymoma may be combined with myasthenia gravis (MG), pure red blood cell aplastic anemia (PRCA), hypoglobulinemia, nephritis nephrotic syndrome, rheumatoid arthritis, dermatomyositis, lupus erythematosus, and megalophagia, with myasthenia gravis being the most common. Traditional typing is named after the cellular component that accounts for more than 80% of the disease, and is divided into epithelial cell type, lymphocytic type and mixed epithelial lymphocytic type. There are other types of thymoma, including cortical, medullary and mixed types, and cortical type is divided into two subtypes: cortical-dominant type and “pure” cortical type. Currently, the histological classification of thymoma is based on the 1999 WHO classification of thymoma: Type A thymoma: medullary or spindle cell thymoma. AB thymoma: i.e., mixed thymoma. Type B thymoma: classified into 3 subtypes; Type B1 thymoma: i.e. lymphocyte-rich thymoma, lymphocytic thymoma, cortical-dominant thymoma, or organoid thymoma; Type B2 thymoma: i.e. cortical thymoma; Type B3 thymoma: i.e. epithelial, atypical, squamous-epithelioid thymoma, or well-differentiated thymic carcinoma. Type C thymoma: i.e. thymic carcinoma, histologically this type has more malignant features than the other types of thymoma. Stage I: complete pericardium with no microscopic extrapericardial invasion; Stage II: microscopic invasion of the pericardium or invasion of mediastinal adipose tissue or mediastinal pleura; Stage III: visual invasion of adjacent structures (e.g. pericardium, great vessels or lung); Stage IVA: pleural cavity dissemination (pleural or pericardial metastasis); Stage IVB: lymphatic or hematogenous metastasis, extrapleural dissemination (bone metastasis is most common).