Thyroid Cyst
A thyroid cyst is a fluid-filled sac or pocket that forms within the thyroid gland, which is located in the front of the neck. Thyroid cysts are relatively common and are usually benign (noncancerous). They can vary in size from very small to several centimeters in diameter.
The exact cause of thyroid cysts is not always known, but they can develop due to various factors, including:
Thyroid nodules: Thyroid cysts can form within preexisting thyroid nodules, which are solid or fluid-filled lumps in the thyroid gland.
Blockage of thyroid ducts: The thyroid gland has small ducts that can become blocked, leading to the accumulation of fluid and the formation of a cyst.
Hormonal imbalances: Changes in hormone levels can contribute to the development of thyroid cysts, although the exact mechanism is not fully understood.

