The Thyroid Nodule
A short summary on the common thyroid nodule risk factors and diagnostic evaluation.
Definition of Thyroid Nodule
Thyroid nodules are soft tissues lesions found within the thyroid gland. They are quite common, and can be found in both adult and pediatric patients.
Approximately 95% of thyroid nodules are benign. The risk of malignant disease increases in young populations (< 20) and older populations (women > 40 and men > 50). The vast majority of malignant thyroid nodules are papillary thyroid carcinoma. Thyroid nodules can also be present in the context of inflammatory diseases of the thyroid, such as Hashimoto's thyroiditis and Grave's disease.
Signs and Symptoms
Increased risk of carcinoma if:
Nodule if firm or fixed
Nodule is > 2 cm
Nodule is solid
Palpable cervical lymph nodes in setting of thyroid nodule
Nodules > 1 cm are typically palpable, depending on anatomy, and require full work-up. Nodules < 1 cm that are found incidentally on imaging require annual monitoring with ultrasound rather than diagnostic work-up.
TSH testing should be performed in all patients found to have thyroid nodules. Those with hyperthyroidism and nodules should undergo Tc99 radionuclide scanning to determine metabolic activity of nodules. Patients with metabolically "cold" nodules have a higher risk of malignancy.
Inquire about family history of thyroid cancer
Inquire about personal history of radiation to the head and neck
Assess for hoarseness or voice changes, difficulty breathing, noisy breathing, or difficulty swallowing. If nodules are > 1cm, referral to otolaryngologist for further evaluation. Patients will require full laryngeal evaluation, ultrasound, and possible fine needle aspiration.
Pearls To Know
Thyroid nodules carry a 20-50% chance of malignancy in patients less than 20 years of age.
Nodules are more common in men over 50 and women over 40 years of age.
Family history of thyroid carcinoma and previous head and neck radiation exposure increases the risk of malignancy for thyroid nodules.
TSH is the initial diagnostic study in the work-up of all thyroid nodules > 1cm in size.
Fine Needle Aspiration (FNA) is the gold standard for diagnosis. It is 99% effective in detecting papillary thyroid carcinoma, has <1% false positive rate, and a 1-6% false negative rate. It has decreased the need for thyroid surgery by 35-75% in patients with thyroid nodules. Most otolaryngologists will perform this under ultrasound guidance or refer patients to an interventional radiologist for harder to reach lesions.
After FNA, the Bethesda Criteria are used by cytopathologists to determine the risk of malignancy for a nodule in question.
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Lai SY, Mandel SJ, Weber RS. Management of Thyroid Neoplasms. In: Flint PW, Haughey BH, Lund V, Niparko JK, Robbins KT, Thomas R, Lesperance MM. Cummings Otolaryngology. 6th ed. Philadelphia, PA: Saunders; 2015.