Approach to the Thyroid Incidental Nodule

1. Approach to the Thyroid Incidental Nodule Author: Thomas Hope, MD Editor: Amy Shaheen, MD, Assistant Professor of Clinical Medicine Duke University Medical Center

2. Thyroid Nodules: Incidence • Definition: • A lesion incidentally discovered radiographically measuring >1cm. • Incidence: • 4-7% of all adult patients have a palpable thyroid nodule • 1 in 20 of these nodules is cancerous

3. Benign Multinodular goiter Hashimoto’s thyroiditis Cysts—colloid, simple, hemorrhagic Follicular adenomas Hurthle cell adenomas Malignant Papillary carcinoma Follicular CA—minimally or widely invasive, Hurthle-cell type Medullary carcinoma Anaplastic carcinoma Primary thyroid lymphoma Metastatic carcinoma—breast, renal,etc Thyroid Nodules: Differential Diagnosis (UTDOL) Most common diagnoses: colloid nodules, cysts, and thyroiditis (80%), benign follicular neoplasms (10-15%), thyroid CA (5%) (Hegedus, NEJM 2004)

4. Thyroid Nodules: Risk factors for malignancy • High suspicion: Family hx of medullary thyroid CA or MEN, rapid tumor growth, very firm/hard nodule, fixation of nodule to adjacent structures, paralysis of vocal cords, regional lymphadenopathy, distant metastases • Moderate suspicion: Age <20 or >70, male sex, hx head/neck irradiation, nodule >4cm or partially cystic, symptoms of compression—dysphagia, hoarseness, dysphonia • If two or more high suspicion risk factors present, cancer is the diagnosis nearly 100% of time.

5. Thyroid Nodules: General approach to incidental palpable thyroid nodule • Step 1: Check TSH. • If TSH is low  the likelihood is for a benign “hot nodule”. The next step is a thyroid radionuclide uptake scan. If “hot nodule” is present, initiate appropriate therapy if needed, without need for biopsy. • If TSH is high  check anti-thyroperoxidase antibodies to try to rule in Hashimoto’s thyroiditis. Even if positive, however, a coexisting cancer could be present, making FNA necessary anyway (proceed to step 2). • If TSH is normal  proceed to step 2. • If there is a family history of medullary thyroid cancer or MEN-2  a serum calcitonin should be checked (will be high in medullary thyroid CA). Then proceed to step 2.

6. Thyroid Nodules: General approach to incidental palpable thyroid nodule (2) • Step 2: FNA-- with ultrasound guidance. Notice that a plain thyroid ultrasound is not the recommended next step—it does not obviate the need for a FNA. FNA can distinguish benign nodules, papillary carcinoma, or follicular neoplasm, but not between follicular adenoma and follicular carcinoma.

7. Thyroid Nodules: General approach to incidental palpable thyroid nodule (3) • Step 3: Surgery (for suspicious or malignant nodules on FNA--including follicular neoplasm) or follow up (confirmed benign nodule on FNA). Alternative treatments for a benign nodule include levothyroxine therapy, surgery, ethanol injections—any of these should be guided by an endocrinologist, i.e. Dr. Warner Burch, Duke’s thyroid expert. • NOTE: According to expert opinion (er…UTDOL), a thyroid nodule <1 cm found incidentally on an unrelated imaging study (i.e. carotid Doppler ultrasound) enters a realm of controversy. Studies are cited for and against FNA, with no clear recommendation. The 1996 AACE guidelines (have times changed since then?) recommend conservative follow up (i.e. serial physical exams) unless risk factors or suspicious nodule characteristics are present. A nodule >1cm should follow the guidelines for the palpable nodule.

8. Thyroid Nodules: Algorithm for incidental palpable thyroid nodule Click here to view a .pdf file of this algorithm Note: This algorithm is included as an attachment from this presentation as well as a module listing in the course outline

9. Thyroid Nodules: Question (1) A 42-year-old woman presents with a palpable mass on the leftside of her neck. She has no neck pain and no symptoms of thyroiddysfunction. Physical examination reveals a solitary, mobilethyroid nodule, 2 cm by 3 cm, without lymphadenopathy. The patienthas no family history of thyroid disease and no history of externalirradiation.

10. Question

11. Thyroid Nodules: Correct Answer rationale (1) A) All patients with a thyroid nodule should have a TSH checked, followed by either an FNA if the result is normal or high, or a radionuclide scan if low. A thyroid ultrasound does not avoid the need for a FNA, so it should not be ordered without a plan for simultaneous biopsy. Tissue is preferred prior to surgery (even for high risk patients, where the pathology may guide surgical approach). A serum calcitonin level would be important to order with the TSH if the patient had a family history of medullary thyroid cancer or MEN-2. (source: Hegedus, NEJM 2004)

12. Thyroid Nodules: Question (2) A 37 y/o asymptomatic woman presents for a routine physical examination. Physical examination reveals a 2-cm right-sided thyroid nodule that is firm, non-tender and moves with swallowing. The rest of the physical exam is unremarkable, including normal reflexes and absence of tremor. The TSH level is 1.8. She is referred for fine-needle aspiration biopsy of the thyroid nodule.

13. Question 2

14. Thyroid Nodules: Correct Answer rationale (2) D) When adequate samples are obtained from FNA (less likely with cystic lesions), approximately 85% of nodules are benign adenomatoid, cellular, or cystic. A certain proportion can be characterized as papillary cancers. However, FNA biopsy cannot distinguish between malignant and benign follicular neoplasms because these entities are cytologically identical. Thus, in many cases, patients with papillary carcinoma or follicular neoplasm on FNA biopsy are referred for surgery (source: MKSAP-13)

15. Thyroid Nodules: Sources • Hegedus L, Clinical Practice: The Thyroid Nodule, NEJM 2004, 351(17):1764-1771 • AACE Clinical Guidelines for the Diagnosis and Management of Thyroid Nodules, AACE Thyroid Nodule Task Force, 1996. • Up to Date, 2005.