We welcome patients to visit the Cardiothoracic Surgery Department of Tianjin Medical University General Hospital or through our online consultation, Dr. Dong’s consultation website. We will promptly answer your questions, develop individualized treatment plans and provide the next step of treatment according to your condition as much as possible. Thymoma is a tumor derived from thymic epithelial cells. Unlike other tumors, the benign and malignant nature of thymoma cannot be determined based on histology, and its benign and malignant nature should be judged based on the presence or absence of envelope infiltration, surrounding organ invasion or distant metastasis. Some scholars use the term “benign thymoma” to describe a non-invasive thymoma. In fact, recurrence and metastasis can occur after surgical resection of thymoma of any tissue type, including stage I. Therefore, all thymomas are currently considered potentially malignant, and the term “benign thymoma” should be discarded. In order to avoid mentioning “malignant”, it is currently advocated to classify thymomas as non-invasive or invasive. In general, 30% to 40% of thymomas are invasive. The traditional histological classification is based on the ratio of non-neoplastic lymphocytes to tumor epithelial cells in the tumor, which is divided into lymphocytic type, mixed cell type, and epithelial cell type, and this classification has been used for many years, but since it cannot determine the benignity and malignancy of the tumor, let alone the prognosis, and most patients are of mixed type, it has little clinical guidance. 1985 et al. proposed a new classification method: based on Histologically and immunophenotypically based typing, similar to the cortical or medullary regions of the thymus, into medullary, mixed, cortical-dominant and cortical types, and this classification was widely used. In order to better relate the histological typing of thymoma to the aggressiveness and prognosis of the disease, in 1999, WHO developed an updated classification of thymic epithelial tumors, which uses a classification method and classifies thymomas into A, B, AB based on the morphology of epithelial cells and the ratio of lymphocytes to epithelial cells.
3 types, type A tumors consist of shuttle-shaped tumor epithelial cells without atypical or tumor lymphocytes; type B tumors consist of round epithelial-like cells; type AB is a mixture of both manifestations, similar to type A, but containing tumor lymphocytes. Based on the proportional increase of epithelial cells and the appearance of atypical tumor cells, type B tumors are further divided into three subtypes: type B1, type B2, and type B3. All thymic carcinomas are type C. The new WHO classification relates to the classification of