A cyst, by definition, contains fluid. Thyroid cysts are regions of the thyroid that are enlarged and filled with fluid. They may be small (1 cm) or sometimes very large and can develop slowly or arise suddenly. Thyroid nodules can also degenerate and become fluid-filled sacs entirely or have a combination of solid and cystic areas.
Pure thyroid cysts may be managed in a variety of ways. Most commonly, pure thyroid cysts which are 3cm or less in size are merely observed and monitored for changes. Alternative management approaches for thyroid cysts are many including aspiration and instillation of ethanol or other ablative approaches.
Thyroid cysts are not very common. They are a type of thyroid nodule or lump. Though it has been estimated that between 10 and 50 percent of the population may have thyroid nodules, thyroid cysts make up only a small portion of that number.
Thyroid cyst. Fluid-filled cavities (cysts) in the thyroid most commonly result from degenerating thyroid adenomas. Often, solid components are mixed with fluid in thyroid cysts. Cysts are usually benign, but they occasionally contain malignant solid components. Chronic inflammation of the thyroid (thyroiditis).
Thyroid cysts are not as common as solid thyroid nodules but they are still important to understand. It's helpful to think of thyroid cysts as a subtype of thyroid nodules but one that is usually completely filled with fluid. The majority of cysts are benign and not dangerous.
Thyroid cancer is a cancer that starts in the thyroid gland, a small butterfly-shaped gland located in the middle of the neck below the Adam’s apple. Thyroid cancer is relatively common, with 62,980 new cases reported in the United States in 2014.
However, degenerating thyroid adenomas are the most common cause of thyroid cysts specifically, according to Mayo Clinic. A thyroid adenoma is an overgrowth of normal thyroid tissue. A thyroid cyst is a growth within the thyroid gland that is either completely fluid-filled or partially solid and partially fluid-filled, explains Cleveland Clinic.
Both can be malignant, although it’s more common for a thyroid nodule to be malignant than a thyroid cyst. The only way to confirm a malignancy is through a fine needle aspiration. Most Thyroid Nodules and Cysts Don’t Need To Be Removed. In most cases, a thyroid nodule or cyst doesn’t need to be surgically removed.
Abnormal thyroid function tests may occasionally be the reason a thyroid nodule is found. Thyroid nodules may produce excess amounts of thyroid hormone causing hyperthyroidism (see Hyperthyroidism brochure). However, most thyroid nodules, including those that cancerous, are actually non-functioning, meaning tests like TSH are normal.
We know that thyroid nodules are much less common in children, but we do not have exact numbers. There is an increased risk of thyroid cancer in nodules found in children and adolescents compared to adults; however, even in children, most thyroid nodules are benign (not cancer).