Snapshot A 22-year-old woman presents to her primary care physician after finding a "lump" on her neck. She denies any fever, flu-like symptoms, or sick contacts. She also denies any pain or discomfort in the neck; however, she notes an unintentional 8-pound weight loss. She does not have any significant medical history. Family history is significant for medullary thyroid cancer in her mother and parathyroid hyperplasia in her maternal grandmother. Physical exam is significant for a fixed hard mass in the right-side of the thyroid. A thyroid stimulating hormone level is decreased and thyroid scintigraphy is scheduled to be performed. Introduction Epidemiology Malignant risk factors < 30 or > 70 years of age family history of medullary thyroid cancer multiple endocrine neoplasia (MEN) 2 Cowden syndrome familial adenomatous polyposis history of prior radiation to the neck cold nodule on radioactive iodine uptake cervical lymphadenopathy concerning findings on ultrasound hypoechoic irregular borders microcalcifications central vasculature Benign risk factors family history of autoimmune thyroid disease goiter hyper- or hypothyroidism nodular tenderness Approach to Thyroid Nodules Discovery of a thyroid nodule begin with a thorough history and physical exam this determines the risk factors the patient has for having a malignant or benign nodule thyroid stimulating hormone (TSH) levels should be checked in all patients with a thyroid nodule ↓ TSH perform thyroid scintigraphy (radioactive iodine uptake test) hot definition there is an increased uptake of iodine compared to the surrounding thyroid tissue suggests an autonomously functioning thyroid likely a benign nodule, thus fine needle aspiration (FNA) is not needed cold definition there is less uptake of iodine compared to the surrounding thyroid tissue perform FNA indeterminate perform FNA ↑ or normal TSH perform FNA if the nodule meets sonographic criteria ultrasonography should be check in all patients with a thyroid nodule sonographic pattern high suspicion a hypoechoic nodule that is > 1 cm and with ≥ 1 suspicious features such as irregular margins microcalcifications rim calcifications extrathyroidal extension perform FNA intermediate suspicion a hypoechoic nodule that is > 1 cm with smooth margins perform FNA low suspicion isoechoic, hyperechoic solid nodule, or partially cystic nodule that has eccentric solid areas and is > 1.5 cm perform FNA FNA findings and management benign periodic ultrasound monitoring indeterminate repeat FNA in 2-3 months suspicious for malignancy thyroidectomy malignant (e.g., papillary cancer, medullary thyroid cancer, and anaplastic cancer) thyroidectomy