Fig. 2

a Macroscopic image of the excised thymic tumor. b–d Hematoxylin and eosin staining of the anterior mediastinal tumor. Microscopic invasion into the surrounding adipose fatty tissue beyond the capsular portion is noted only in one part of the tumor (b, arrow). Tumor cells with relatively poor atypia and round nuclei are seen to grow in a fascicular pattern. The tumor shows findings of hypercellularity (c, d)