1. A 79-yr-old woman with bilateral ptosis and neck muscle weakness Brief Hx and course –1MA; left ptosis –3MA; neck muscle weakness –1WA; right ptosis, diplopia Jolly test: right orbicularis oculi, trapezius 에서 decremental response (+) A small soft tissue nodule in the anterior mediastinum

3. A ovoid thymic mass with well demarcated margin After formalin fixation

4. Lobular growth pattern and infiltration into mediastinal fat

5. Infiltration into mediastinal fat

6. Infiltration into mediastinal fat across the fibrous capsule

7. Type B3 Thymoma Type B3 thymoma is an organotypic thymic epithelial tumor predominantly composed of medium-sized round or polygonal cells with slight atypia. The epithelial cells are mixed with a minor component of intraepithelial lymphocytes, resulting in a sheet-like growth of epithelial cells.