Surgical Recall - Ch. 58 Thyroid Gland

Question 1

Define the arterial blood supply to the thyroid.

Answer 1

Two arteries:

1. Superior thyroid artery (first branch of the external carotid artery)
2. Inferior thyroid artery (branch of thyrocervical trunk) (IMA artery rare)

Question 2

What is the venous drainage of the thyroid

Answer 2

Three veins:

1. Superior thyroid vein
2. Middle thyroid vein
3. Inferior thyroid vein

Question 3

Which paired nerves must be carefully identified during a thyroidectomy?

What other nerve is at risk during a thyroidectomy and what are the symptoms?

Answer 3

Recurrent laryngeal nerves, which are found in the tracheoesophageal grooves and dive behind the cricothyroid muscle; damage to these nerves paralyzes laryngeal abductors and causes hoarseness if unilateral, and airway obstruction if bilateral

Superior laryngeal nerves; if damaged, patient will have a deeper and quieter voice (unable to hit high pitches)

Question 4

What is the most common site of conversion of T4 to T3?

Answer 4

Peripheral (e.g., liver)

Question 5

What is Synthroid (levothyroxine): T3 or T4?

What is the half-life of Synthroid?

Answer 5

T4

Half-life: 7 days

Question 6

What do parafollicular cells secrete?

Answer 6

Calcitonin

Question 7

What is the differential diagnosis of a thyroid nodule?

Answer 7

• Multinodular goiter
• Adenoma
• Hyperfunctioning adenoma
• Cyst
• Thyroiditis
• Carcinoma/lymphoma
• Parathyroid carcinoma

Question 8

Name three types of nonthyroidal neck masses.

Answer 8

1. Inflammatory lesions (e.g., abscess, lymphadenitis)
2. Congenital lesions (i.e., thyroglossal duct [midline], branchial cleft cyst [lateral])
3. Malignant lesions:
   
   1. Lymphoma
   2. Metastases
   3. SCC

Question 9

Thyroid Nodule

1. What studies can be used to evaluate a thyroid nodule?
2. What is the diagnostic test of choice for thyroid nodule?
3. Hot vs. cold nodule?
4. What are the indications for a ¹²³I scintiscan?
5. What is the most common cause of thyroid enlargement?
6. What is Plummer’s disease?

Answer 9

Thyroid Nodule

1. Studies:
   
   1. U/S–solid or cystic nodule
   2. FNA –> cytology
   3. ¹²³I scintiscan–hot or cold nodule
2. Dx test of choice for thyroid nodule? FNA
3. Nodule uptake of IV ¹³¹I or ⁹⁰mT
   
   1. Hot = Increased ¹²³I uptake = functioning/hyperfunctioning nodule
   2. Cold = Decreased ¹²³I uptake = nonfunctioning nodule
4. Indications:
   
   1. Nodule with multiple “nondiagnostic” FNAs with low TSH
   2. Nodule with thyrotoxicosis and low TSH
5. Multinodular goiter
6. Toxic multinodular goiter

Question 10

Thyroid Carcinoma

1. Name the FIVE main types of thyroid carcinoma and their relative %
2. What are the signs/sx?
3. What comprises the workup?
4. What oncogenes are associated with thyroid cancers?

Answer 10

Thyroid Carcinoma

1. Name the FIVE main types of thyroid carcinoma and their relative %
   
   1. Papillary carcinoma: 80%
   2. Follicular: 10%
   3. Medullary: 5%
   4. Hurthle cell: 4%
   5. Anaplastic/undifferentiated: 1%
2. ​Mass/nodule, lymphadenopathy; most are euthyroid
3. FNA, thyroid U/S, TSH, calcium level, CXR, +/- scintiscan ¹²³I
4. Ras gene family and RET protooncogene

Question 11

Papillary Adenocarcinoma

1. What is the environmental risk?
2. What are the associated histological findings?
3. Describe the route and rate of spread.
4. ¹³¹I uptake?
5. What is the 10 year survival rate?
6. What is the treatment for: <1.5 cm and no hx of neck radiation exposure?
7. What postop medication should be administered?
8. What is the most common site of distant mets?

Answer 11

Papillary Adenocarcinoma

1. What is the environmental risk? Radiation exposure
2. What are the associated histological findings? Psammoma bodies (round, laminar collections of calcified tissue)
3. Describe the route and rate of spread. Most spread via lymphatics (cervical adenopathy); spread occurs slowly
4. ¹³¹I uptake? Good uptake… so perform postop ¹³¹I scan to dx/treat metastases
5. What is the 10 year survival rate? 95%
6. What is the treatment for: <1.5 cm and no hx of neck radiation exposure? Thyroid lobectomy and isthmectomy / Total thyroidectomy
7. What postop medication should be administered? TH replacement, to suppress TSH
8. What is the most common site of distant mets? Pulmonary (lungs)

Question 12

Follicular adenocarcinoma

1. Describe the nodule consistency.
2. What is the route of spread?
3. ¹³¹I uptake?
4. What is the overall 10-year survival rate?
5. Can the diagnosis be made by FNA?
6. What histologic findings define malignancy in follicular cancer?
7. What is the most common site of distant metastasis?
8. What is the treatment for follicular cancer?

Answer 12

Follicular adenocarcinoma

1. Describe the nodule consistency. Rubber, encapsulated.
2. What is the route of spread? Hematogenous, more aggressive than papillary adenocarcinoma
3. ¹³¹I uptake? Good uptake…
4. What is the overall 10-year survival rate? 85%
5. Can the dx be made by FNA? NO; tissue structure needed for dx
6. What histologic findings define malignancy in follicular cancer? Capsular or blood vessel invasion
7. What is the most common site of distant metastasis? Bone
8. What is the treatment for follicular cancer? Total thyroidectomy

Question 13

Hurthle Cell Thyroid Cancer

1. What is the cell of origin?
2. ¹³¹I uptake?
3. How is the dx made?
4. What is the route of metastasis?
5. What is the tx?
6. What is the 10-year survival rate?

Answer 13

Hurthle Cell Thyroid Cancer

1. What is the cell of origin? Follicular cells
2. ¹³¹I uptake? No uptake
3. How is the dx made? FNA can identify cells, but malignancy can be determined only by tissue histology (like follicular cancer)
4. What is the route of metastasis? Lymphatic > hematogenous
5. What is the tx? Total thyroidectomy –> RADIOIODINE ABLATION
6. What is the 10-year survival rate? 80%

Question 14

Medullary Carcinoma

1. With what other conditions is it associated?
2. Histology?
3. What does it secrete?
4. What is the appropriate stimulation test?
5. Describe the route of spread.
6. How is the dx made?
7. ¹³¹I uptake?
8. What is the associated genetic mutation?
9. What is the 10-year survival rate?
10. What should all pts with medullary thyroid cancer also be screened for?
11. What is the tx?

Answer 14

Medullary Carcinoma

1. With what other conditions is it associated? MEN type II; AD genetic transmission
2. Histology? Amyloid
3. What does it secrete? Calcitonin (tumor marker) –> can cause diarrhea and flushing symptoms
4. What is the appropriate stimulation test? Pentagastrin (causes an increase in calcitonin
5. Describe the route of spread. Lymphatic and hematogenous distant metastasis
6. How is the dx made? FNA
7. ¹³¹I uptake? Poor uptake
8. What is the associated genetic mutation? RET proto-oncogene
9. What is the 10-year survival rate? 80% w/o LN involvement, 45% with LN spread
10. What should all pts with medullary thyroid cancer also be screened for? MEN II: pheo, HPTH
11. What is the tx? Total thyroidectomy and median lymph node dissection… modified neck dissection, if lateral cervical nodes are positive

Question 15

Anaplastic Carcinoma

1. What is it?
2. What is the gender preference?
3. What are the associated histologic findings?
4. ¹³¹I uptake?
5. How is the dx made?
6. What is the major differential dx?
7. What is the tx of the following disorders:
   
   1. Small tumors?
   2. Airway compromise?
8. What is the prognosis?

Answer 15

Anaplastic Carcinoma

1. What is it? Undifferentiated cancer arising in ~75% of previously differentiated thyroid cancers (most commonly, follicular)
2. What is the gender preference? Women > Men
3. What are the associated histologic findings? Giant cells, spindle cells
4. ¹³¹I uptake? Very poor uptake
5. How is the dx made? FNA (large tumor)
6. What is the major differential dx? Thyroid lymphoma (much better prognosis!)
7. What is the tx of the following disorders:
   
   1. Small tumors? Total thyroidectomy + XRT/chemo
   2. Airway compromise? Debulking surgery + tracheostomy, XRT/chemo
8. What is the prognosis? Dismal, b/c most pts are at stage IV at presentation (3% alive in 5 years)

Question 16

What laboratory value must be followed post-op after a thyroidectomy?

Answer 16

Calcium decreased 2/2 parathyroid damage

Question 17

What is the differential dx of post-op dyspnea after a thyroidectomy?

Answer 17

• Neck hematoma (remove sutures and clot at the bedside)
• Bilateral recurrent laryngeal nerve damage

Question 18

Graves’ disease

1. What is Graves’ disease?
2. What is the etiology?
3. How is the dx made?
4. Name tx option modalities for Graves’ disease.
5. How does PTU and methimazole work?

Answer 18

Graves’ disease

1. What is Graves’ disease? Diffuse goiter with hyperthyroidism, exophthalmos, and pretibial myxedema
2. What is the etiology? Caused by circulating antibodies that stimulate TSH receptors on follicular cells of the thyroid –> deregulated production of thyroid hormones (i.e., hyperthyroidism)
3. How is the dx made? Increased T3, T4, and anti-TSH receptor antibodies, decreased TSH, global uptake of ¹³¹I radionuclide
4. Name tx option modalities for Graves’ disease.
   
   1. Medical blockade: iodide, propranolol, PTU, methimazole, Lugol’s sol’n (KI)
   2. Radioiodide ablation: most popular!
   3. Surgical resection: bilateral subtotal thyroidectomy
5. PTU: inhibits incorporation of iodine into T4/T3 (by blocking peroxidase oxidation of iodide to iodine) AND inhibits peripheral conversion of T4 to T3…. Methimazole: inhibits incorporation of iodine into T4/T3 ONLY (by blocking “ “)

Question 19

Toxic Multinodular Goiter

1. What is it also known as?
2. What is it?
3. What medication may bring on hyperthyroidism with a multinodular goiter?
4. How is the hyperfunctioning nodule(s) localized?
5. What is the tx?
6. What is Pemberton’s sign?

Answer 19

Toxic Multinodular Goiter

1. What is it also known as? Plummer’s disease
2. What is it? Multiple thyroid nodules with one or more nodules producing thyroid hormone, resulting in hyperfunctioning thyroid (hyperthyroidism or a “toxic” thyroid state)
3. What medication may bring on hyperthyroidism with a mltinodular goiter? Amiodarone
4. How is the hyperfunctioning nodule(s) localized? ¹³¹I radionuclide scan
5. What is the tx? Surgically remove hyperfunctioning nodule(s) with lobectomy or near total thyroidectomy
6. What is Pemberton’s sign? Large goiter causes plethora of head with raising of both arms

Question 20

Thyroiditis

1. What are the features of ACUTE thyroiditis?
2. What is the cause of ACUTE thyroiditis?
3. Tx?
4. What are the features of SUBACUTE thyroiditis?
5. What is the cause of SUBACUTE thyroiditis?
6. Tx?
7. What is De Quervain’s thyroiditis?

Answer 20

Thyroiditis

1. What are the features of ACUTE thyroiditis? Painful, swollen thyroid; fever; overlying skin erythema; dysphagia
2. What is the cause of ACUTE thyroiditis? Bacteria (usually Streptococcus or Staph), usually caused by a thyroglossal fistula or anatomic variant
3. Tx? Abx, drainage of abscess, needle aspiration for culture; most pts need definitive surgery later to remove the fistula
4. What are the features of SUBACUTE thyroiditis? Glandular swelling, tenderness, often follows URI, elevated ESR
5. What is the cause of SUBACUTE thyroiditis? Viral
6. Tx? Supportive: NSAIDS, +/- steroids
7. What is De Quervain’s thyroiditis? Just another name for SUBACUTE thyroiditis caused by a virus (think “V”)

Question 21

Thyroiditis

1. What are the two types of chronic thyroiditis?
2. What are the features of Hashimoto’s (chronic) thyroiditis?
3. What is the etiology?
4. What lab tests should be performed to dx?
5. Tx?
6. What is Riedel’s thyroiditis?
7. Tx?

Answer 21

Thyroiditis

1. What are the two types of chronic thyroiditis?
   
   1. Hashimoto’s
   2. Riedel’s
2. What are the features of Hashimoto’s (chronic) thyroiditis?
   
   1. Firm and rubbery gland, 95% in women, lymphocyte invasion
3. ​Etiology: AI
4. Antithyroglobulin, and microsomal antibodies
5. Tx: TH replacement if hypothyroid (surgery is reserved for compressive sx and/or if cancer needs to be r/o)
6. Riedel’s: Benign inflammatory thyroid enlargement WITH FIBROSIS of thyroid… pts present with painless, large thyroid… fibrosis may involve surrounding tissues
7. Tx: Surgical tracheal decompression, TH replacement as needed–possibly steroids/tamoxifen if refractory