Thymoma type B1 arising in a giant supradiaphragmatic thymolipoma.

Thymolipomas are uncommon tumors of the anterior mediastinum. They may extend into, but rarely stem from, the chest cavity. Furthermore, thymoma arising in a thymolipoma is extremely rare. We report a unique case of thymoma type B1 that originated form a giant thymolipoma located in the chest cavity, which was resected by a lateral thoracotomy in a 23-year-old woman. To our knowledge, this is the first reported case of thymoma type B1 arising within a giant thymolipoma.