Thyroid Nodule
A thyroid nodule is a discrete growth or lump within the thyroid gland, the butterfly-shaped gland located at the front of the neck that helps regulate metabolism and hormone balance. Thyroid nodules are extremely common, and most are benign. A smaller percentage may represent thyroid cancer or affect thyroid hormone production. Nodules may be solid, fluid-filled, or mixed and are often discovered during physical examination, ultrasound, or imaging performed for unrelated reasons.
What is it?
The thyroid gland produces hormones that help regulate energy use, body temperature, heart rate, and many other metabolic functions. A thyroid nodule is a focal area within the gland that differs in appearance or texture from the surrounding thyroid tissue.
Nodules may be solid, cystic (fluid-filled), or partially cystic. Some people have a single thyroid nodule, while others have multiple nodules within an enlarged thyroid gland, a condition often referred to as multinodular goiter.
Most thyroid nodules are benign and may represent simple cysts, benign adenomas, areas of tissue overgrowth, or inflammatory changes such as Hashimoto’s thyroiditis. A smaller percentage—generally estimated at approximately 5–10%—are malignant.
Risk factors that may increase concern for thyroid cancer include prior radiation exposure to the neck, family history of thyroid cancer, certain inherited syndromes, rapid growth, and suspicious imaging features.
Ultrasound is the preferred imaging test for evaluating thyroid nodules because it provides highly detailed assessment of the thyroid gland and individual nodules. Ultrasound evaluates features such as size, composition, calcifications, margins, shape, and blood flow.
Standardized systems such as TI-RADS are commonly used to estimate cancer risk and determine whether fine-needle aspiration biopsy is recommended.
Blood tests including TSH and sometimes T3 and T4 help determine whether the thyroid gland is functioning normally or whether the nodule is affecting hormone production.
CT and MRI are not typically used for routine thyroid nodule evaluation but may be helpful when large goiters extend into the chest or when surrounding structures need additional assessment.
Important to Know
Many thyroid nodules require no treatment beyond periodic ultrasound follow-up. When imaging features or size raise concern, fine-needle aspiration biopsy may be recommended to collect cells for microscopic evaluation.
Biopsy results are commonly reported using the Bethesda classification system, which helps guide further management decisions.
Benign nodules causing symptoms such as swallowing difficulty, airway compression, or cosmetic concerns may sometimes require medication or surgery. Hyperfunctioning nodules that produce excess thyroid hormone may be treated with medication, radioactive iodine, or surgery.
When biopsy findings suggest thyroid cancer or suspicious changes, treatment is typically coordinated through endocrinology and surgical specialists. Most thyroid cancers are highly treatable, particularly when identified early.
Follow-up ultrasound imaging is commonly used to monitor nodule stability and growth over time.
Red flag features include rapid enlargement of a thyroid nodule, persistent hoarseness, difficulty swallowing or breathing, enlarged neck lymph nodes, or a history of neck radiation or family thyroid cancer syndromes. These symptoms warrant prompt medical evaluation.