What is a 3mm anechoic cyst of the thyroid?

A 3mm anechoic cyst of the thyroid is a small fluid-filled sac within the thyroid gland that appears dark or "anechoic" on ultrasound imaging due to the absence of internal echoes. These cysts are typically benign and often do not require treatment unless they cause symptoms or show signs of growth. The size of 3mm indicates that it is relatively small, and most anechoic cysts of this size are considered clinically insignificant. Regular monitoring may be recommended to ensure no changes occur over time.