A 33-year-old male presents with ptosis (drooping eyelid), trouble masticating and swallowing, and notices he feels fatigued quickly. An anterior mediastinal mass, 3.5cm in diameter, was found after a CT scan. Histological analysis after biopsy resulted in the slide below.

mm-pg1.png

You conclude the mass originated from:

Thyroid
Lymph Node
Thymus
Parathyroid