How is drop metastasis of thymoma?

It goes to ipsilateral pleura/pericardium/ upper abdomen (through diaphragmic hiatus) mediastinal invasion may be detected by CT (irregular tumoral surface, contralateral extension of thymoma across midline and invasion of mediastinal fat (MRI more sensitive for vascular invasion) PET is useful for invasions Guided needle biopsy used for dx (but may not be required before excision in classic thymoma)