Also known as well-differentiated thymic carcinoma, atypical thymoma, or epithelial thymoma, this type of thymoma displays morphologic characteristics of a well-differentiated carcinoma. The majority of cases occur in the anterior mediastinum as Masaoka stage II or stage III tumors. It is almost always invasive, it recurs frequently, and metastasizes in approximately 20% of the cases. The disease is thymoma type B3 (MONDO_0006458). Also known as: atypical thymoma, epithelial malignant thymoma, epithelial thymoma, malignant thymoma type B3, squamoid thymoma, thymoma, epithelial, well differentiated thymic carcinoma, well-differentiated thymic carcinoma.