Thyroid Nodules1

Question 1

What are the risk factors for thyroid nodules?

Answer 1

Thyroid nodules are four times more common in women, and they are more common with advancing age, radiation exposure, family history of goiter, and iodine deficiency.

Question 2

What is the most common type of thyroid cancer?

Answer 2

Papillary thyroid cancer is the most common type of thyroid cancer (about 85%), followed by follicular (10%), medullary (5%), and anaplastic (1%) cancers. Rare forms of thyroid cancer include lymphoma, metastatic nodules, and teratomas.

Question 3

What percentage of thyroid nodules are malignant?

Answer 3

3-5%. Most are benign.

Question 4

T/F: Most thyroid nodules are symptomatic.

Answer 4

FALSE

Question 5

What is the Pemberton sign?

Answer 5

Patients are tested for Pemberton sign by asking them to raise their arms overhead. A positive sign is when the maneuver is followed by facial discoloration and venous enlargement, which is seen in patients with large retrosternal goiters that narrow the thoracic inlet.

Question 6

What is the single best test of thyroid function?

Answer 6

Thyrotrophin or thyroid-stimulating hormone (TSH) test

Question 7

In patients with abnormal TSH, what is the next test to be order?

Answer 7

Measurement of both T3 and T4

Question 8

What blood tests will reliably distinguish between benign and malignant thyroid disease?

Answer 8

There are no currently available blood tests to reliably distinguish between benign and malignant thyroid disease. Thyroglobulin is increased in both benign and malignant disease.

Question 9

What is the most useful imaging test to evaluate thyroid nodules?

Answer 9

Ultrasound of the neck by an experienced ultrasonographer

Question 10

Which ultrasound characteristics of thyroid nodules are worrisome for malignancy?

Answer 10

Hypoechoic nodules, nodules with irregular borders, or those that are ill defined. Nodules with an absent colloid halo sign and those with microcalcifications are also suspicious, as they are more common in patients with papillary thyroid cancer.

Question 11

What is the role of thyroid scintigraphy?

Answer 11

Thyroid scan results can help differentiate between toxic thyroid adenoma, Plummer disease, and Graves disease.

Question 12

In what circumstances, a CT or MRI is needed for patients with thyroid nodules?

Answer 12

Retrosternal goiters or patients with locally advanced thyroid cancer. They both can define the presence and extent of retrosternal goiters and whether there is associated tracheal compression and/or deviation as well as provide additional anatomic information with regard to vascular and tracheal involvement.

Question 13

What is the best test to evaluate thyroid nodules?

Answer 13

FNA

Question 14

What classic cytologic findings are seen in papillary thyroid carcinoma?

Answer 14

Nuclear crowding, cytoplasmic clearing with the so-called ﾓOrphan Annie eyes,ﾔ and nuclear grooves.

Question 15

What classic cytologic findings are seen in medullary thyroid carcinoma?

Answer 15

Medullary thyroid cancers lack colloid, have spindle-shaped cells, and often have amyloid and apple-green birefringement under polarized light. Immunohistochemical staining with calcitonin is diagnostic.

Question 16

What classic cytologic findings are seen in anaplastic thyroid carcinoma?

Answer 16

Anaplastic cancers have characteristic hypercellularity with necrosis and cellular pleomorphism.

Question 17

Which types of thyroid cancers cannot be diagnosed by FNA?

Answer 17

Follicular and Hurthle cell thyroid cancers cannot be diagnosed using FNA. Follicular cancer is cytologically bland; it is not characterized by classic cellular changes. Cytology usually reveals clumps of follicular cells with a microfollicular pattern. The diagnosis of carcinoma is dependent on histology rather than cytology, with a full evaluation of the nodule capsule for evidence of vascular or capsular invasion. Follicular neoplasms are associated with about a 20% risk of malignancy, usually prompting the recommendation for a thyroid lobectomy.

Question 18

What are the four classications for a FNA result?

Answer 18

1) nondiagnostic
2) benign
3) indeterminate/suspicious (follicular or hurthle cell neoplasm)
4) malignant.

Question 19

What is an appropiate follow up for a patient with a benign FNA?

Answer 19

Benign FNA results can be followed with repeat ultrasound examination in 6 months to 1 year.

Question 20

In which patients, you should consider diagnostic surgery for thyroid nodules?

Answer 20

1. Patients with FNA findings suggestive of a follicular or Hurthlr cell neoplasm
2. Growing nodule, even if FNA is benign

Question 21

Which patients will and will not benefit from an intraoperative frozen-section analysis of a thyroid nodule?

Answer 21

Helpful for nodules suspicious for papillary thyroid cancer but not follicular or Hurthle cell nodules.

Question 22

What is important to know about treatment of thyroid nodules in pregnant patients?

Answer 22

1. FNA should be recommended for thyroid nodules larger than 1 cm
2. When FNA reveals thyroid cancer, or when nodules rapidly grow, surgery can be offered in the second trimester
3. Suppressive doses of thyroid hormone can be given postoperatively
4. Radioactive isotope administration withﾠ131 I should not be given during pregnancy and lactation. Women treated postpartum with radioiodine should wait 6 months to 1 year before conceiving.