Type b3 thymoma is not a clinical stage of thymic carcinoma, it is a histologic staging of thymoma, which is highly malignant. Early or late stage depends on the clinical staging. WHO proposes a typing method based on the morphology of epithelial cells and the ratio of lymphocytes to epithelial cells in tissues of thymoma, in which type b consists of rounded epithelial cells. type b is further divided into types 1, 2 and 3, and correspondingly is low malignant, moderately malignant and highly malignant, respectively. Clinical staging divides the tumor into stages I-IV. Stage I tumors are confined to the thymus without peritumoral infiltration. Stage II tumors extend beyond the thymic envelope and can involve the surrounding fat. Stage III tumors further invade adjacent tissues or organs. In stage IV, the tumor extensively invades the pleura and pericardium or has distant spread and metastasis. If the thymoma does not occur surrounding tissue infiltration, no lymph node metastasis and distant metastasis, it is early stage. If thymoma tumor is large, with obvious invasion of surrounding tissues and distant and lymph node metastasis, thymoma is in middle or even late stage. It is suggested that patients with thymoma should go to regular hospitals for consultation in time and listen to professional doctors’ opinions.