A 34-year-old woman comes to the office due to fullness in her neck after noticing a difference in how jewelry rests around her neck as compared to before. The patient has no other symptoms. She has no medical issues and takes no medications. Family history includes thyroid surgery for an enlarged thyroid gland in her mother. Examination reveals a 1.4-cm firm, nontender, mobile nodule in her left thyroid lobe. The remainder of the physical examination is unremarkable. Laboratory evaluation shows serum TSH of 0.25 µU/mL, serum total thyroxine (T4) of 10 µg/dL, and serum triiodothyronine (T3) of 176 ng/dL. A thyroid ultrasound reveals a 1.4-cm left thyroid nodule with smooth margins and no microcalcifications or internal vascularity. Which of the following is the most appropriate next step?

Question

A 34-year-old woman comes to the office due to fullness in her neck after noticing a difference in how jewelry rests around her neck as compared to before.  The patient has no other symptoms.  She has no medical issues and takes no medications.  Family history includes thyroid surgery for an enlarged thyroid gland in her mother.  Examination reveals a 1.4-cm firm, nontender, mobile nodule in her left thyroid lobe.  The remainder of the physical examination is unremarkable.  Laboratory evaluation shows serum TSH of 0.25 µU/mL, serum total thyroxine (T4) of 10 µg/dL, and serum triiodothyronine (T3) of 176 ng/dL.  A thyroid ultrasound reveals a 1.4-cm left thyroid nodule with smooth margins and no microcalcifications or internal vascularity.  Which of the following is the most appropriate next step?

Quizplus · Accepted Answer

Explanation: 11ec25c8_d8cf_6532_bc81_1788784e6592_MD0003_00 Thyroid nodules are common and may be diagnosed on physical examination or noted incidentally when imaging studies are obtained for other reasons. Once a thyroid nodule is found, cancer risk factors (eg, family history, radiation exposure) should be assessed by history. Physical examination should evaluate the size, mobility, and firmness of the thyroid nodule and check for the presence of enlarged cervical lymph nodes. Serum TSH levels should be obtained, along with a thyroid ultrasound, to determine nodule size and sonographic features. Certain sonographic features (eg, microcalcifications, irregular margins, internal vascularity) carry a much higher risk of malignancy than others (eg, cystic or spongiform lesions). Thyroid nodules >1 cm with these high-risk sonographic features-and all noncystic thyroid nodules >2 cm-should undergo fine-needle aspiration (FNA). If the TSH is low, as seen here, the patient should be evaluated with radionuclide thyroid scan using iodine-123: A hypofunctioning ("cold") nodule (decreased isotope uptake compared to surrounding tissue) is associated with a higher risk of cancer. A hyperfunctioning ("hot") nodule (increased isotope uptake in the nodule with decreased surrounding uptake) is associated with a low cancer risk; therefore, FNA is not necessary (Choice B). This patient who has a thyroid nodule with no concerning sonographic features and a low TSH should receive a radionuclide thyroid scan. (Choice A) A CT scan of the neck is inferior to ultrasound for characterizing thyroid nodules. Even if a thyroid nodule is detected on CT scan, a thyroid ultrasound is still needed. (Choice D) Anti-thyroperoxidase antibody testing can identify chronic autoimmune (Hashimoto) thyroiditis, but it is used for patients with high TSH levels (eg, hypothyroid). (Choice E) Calcitonin is an important tumor marker in medullary thyroid carcinoma (MTC). In patients with a thyroid nodule, testing for calcitonin should be performed if there is a family history of MTC or if cytologic examination (eg, FNA) of the nodule is consistent with MTC. (Choice F) Thyroid stimulating antibodies are present in patients with Graves disease, which can result in hyperthyroidism. However, Graves disease typically causes a diffusely enlarged goiter rather than a focal nodule. Educational objective: The initial evaluation of thyroid nodules includes a serum TSH assay and thyroid ultrasound. Patients with a suppressed TSH should undergo thyroid scintigraphy. Small, hyperfunctioning nodules are rarely malignant and do not usually require fine-needle aspiration. References: 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: the American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer. (http://www.ncbi.nlm.nih.gov/pubmed/26462967)

A 34-Year-Old Woman Comes to the Office Due to Fullness