label: Thymoma Type B3
label_lc: thymoma type b3
description: 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.