Thyroid Nodules
Thyroid nodules are discrete lesions within the thyroid gland that are detectable by ultrasound. They are extremely common -- found in up to 67% of adults on ultrasound. The vast majority are benign. The primary clinical task is identifying the minority that require biopsy or active intervention based on size, ultrasound characteristics, and clinical context.
Symptoms
Most nodules are asymptomatic and found incidentally on imaging done for other reasons. Larger nodules may cause a visible lump in the neck, a sensation of pressure or fullness, difficulty swallowing, or hoarseness if they compress surrounding structures.
Causes and risk
Iodine deficiency, radiation exposure to the head and neck, family history of thyroid cancer, and autoimmune thyroid disease increase nodule risk. Most benign nodules are colloid cysts or adenomas. Malignancy risk is higher in nodules with irregular margins, microcalcifications, taller-than-wide shape, or internal vascularity on ultrasound.
How it is evaluated
Thyroid ultrasound is the first step and stratifies nodules using the ACR-TIRADS system. TSH is measured to identify functional nodules. Fine-needle aspiration (FNA) biopsy is recommended for nodules meeting size and ultrasound criteria. Molecular testing of FNA samples reduces the number of unnecessary surgeries for indeterminate results.
Treatment
Most benign nodules require ultrasound surveillance at 6 -- 24-month intervals. Symptomatic or growing nodules may be managed with radiofrequency ablation. Surgical resection is reserved for confirmed or highly suspicious malignancy, large compressive nodules, or autonomously functioning nodules causing hyperthyroidism.