Where do cysts on the thyroid come from?

Adenomas: The thyroid gland is made up of a cells called follicles that secrete T4 and T3 (liothyronine) through the interaction of iodine. Sometimes, these follicules collace and form adenomas which are essentially an overgrowth. As the adenomas degenerate they can become fluid filled and are known as cyst. They are usually benign but rarely contain malignant components. To be safe, check TSH and get ultrasound.