Snapshot A 36-year-old woman complains of several weeks of hoarseness and difficulty swallowing. She also feels a sense of fullness in her neck. On physical exam there is a palpable, nontender swelling in the front of her neck that moves with swallowing. There is no cervical lymphadenopathy. Lab studies show decreased TSH. Ultrasound of the neck reveals a 2.5 cm hypoechoic thyroid nodule with calcifications and thyroid scintigraphy shows decreased iodine uptake of the nodule compared to surrounding tissues. Introduction Overview primary malignancy of thyroid gland secondary metasteses can occur from other cancers breast, colon, renal, and melanoma Epidemiology Incidence increasing in past 15 years papillary thyroid cancer (most common) has incidence of 15 per 100,000 Demographics papillary more common in women anaplastic more common in elderly Risk factors < 30 or > 70 years of age history of radiation to head/neck family history of medullary thyroid cancer multiple endocrine neoplasia (MEN) syndrome type 2 Cowden syndrome familial adenomatous polyposis Classification Papillary overview 85% of all thyroid cancers female dominance often multifocal risk factors include radiation exposure to the head and neck spreads via lymphatics very good prognosis histology psammoma bodies (calcifications) login to view 1 more bullet ground glass/empty nuclei/"orphan Annie nuclei" login to view 1 more bullet cells organized into papillary "fingers" Follicular carcinoma overview usually unifocal small number evolved from a benign follicular adenoma login to view 2 more bullets spreads hematogenously login to view 1 more bullet good prognosis histology preservation of normal thyroid follicular architecture but with proliferation login to view 1 more bullet Medullary overview derived from calcitonin-synthesizing C cells login to view 2 more bullets 10% of cases associated with MEN syndrome type 2a or 2b login to view 1 more bullet typically unifocal thyroid nodule patients have elevated serum calcitonin (tumor marker) risk factors login to view 2 more bullets histology amyloid (consisting of calcitonin) Anaplastic overview more common in elderly can be superimposed on multinodular goiter or follicular cancer very poor prognosis Presentation Symptoms dysphagia and hoarseness can be due to direct compression by mass can indicate tumor invasion/nerve involvement Physical exam neck mass or palpable thyroid nodule +/- cervical lymphadenopathy suggests metastasis Imaging Thyroid scintigraphy (radioactive iodine uptake test) indications patients with decreased thyroid stimulating hormone (TSH) levels findings "hot" nodule login to view 4 more bullets "cold" nodule login to view 3 more bullets Ultrasonography indications all patients with thyroid nodule findings hypoechoic nodule >1 cm more likely to be malignant high suspicion of malignancy if login to view 5 more bullets intermediate suspicion of malignancy if login to view 1 more bullet Studies TSH levels decreased TSH more concerning for malignancy follow up with thyroid scintigraphy (radioactive iodine uptake test) normal/elevated TSH less concerning for malignancy follow up with ultrasound Serum calcitonin tumor marker for medullary thyroid cancer Fine needle aspiration (FNA) indications all "cold" nodules on radioactive iodine uptake scan nodules that meet high or intermediate suspicion criteria based on ultrasound nodules that are low suspicion on ultrasound but have all of the following properties login to view 3 more bullets Differential Benign thyroid nodule key distinguishing factors more likely to be tender associated hypo- or hyperthyroidism typically "hot" on radioactive iodine uptake test Treatment Medical iodine radiotherapy indications login to view 2 more bullets thyroid hormone supplementation indications login to view 3 more bullets modalities login to view 1 more bullet Surgical thyroidectomy indications login to view 1 more bullet risk of damage to recurrent laryngeal nerve during surgery login to view 1 more bullet Prognosis Papillary very good prognosis Anaplastic very poor prognosis