20. Surgical Treatment of Thyroid disease

Thyroid nodules are more common in women, but a thyroid nodule in a man has a higher relative risk of malignancy.

Radiation exposure (childhood) ⭐

Family history of thyroid cancer (MEN2, medullary)

Rapid growth

Male sex (fewer nodules but higher malignancy risk)

risk factors for thyroid malignancy

Neck fullness

Dysphagia

Dyspnea (tracheal compression)

Hoarseness

symptoms of goiter

Graves disease

_{^{hypervascular thyroid}}

bruit heard over an enlarged thyroid →

stepwise approach to when to find a thyroid nodule

Disorder	First-line treatment
Graves disease	Methimazole (± RAI)
Toxic adenoma	RAI or surgery; RAI commonly used definitive treatment
Toxic multinodular goiter	RAI or surgery
Papillary thyroid cancer	Surgery → ± RAI afterward
Follicular thyroid cancer	Surgery → ± RAI afterward
Medullary thyroid cancer	Surgery
Anaplastic thyroid cancer	Multimodal/palliative treatment; often systemic therapy ± radiation/surgery
Thyroiditis	Usually supportive; β-blocker for hyperthyroid symptoms

Solid + hypoechoic
Irregular/infiltrative margins
Microcalcifications / punctate echogenic foci
Taller-than-wide shape
Extrathyroidal extension
Suspicious cervical lymph nodes

suspicious ultrasound features of a thyroid nodule

fine needle aspiration

gold standard for diagnosis of thyroid nodule

HOT nodules

the hyperfunctioning thyroid nodules seen on a nuclear medicine study that are almost always benign

-no FNA needed

“Cancer, Compression, or Function.”

_{Cancer → malignant/suspicious cytology (goes off bethesda stages)
Compression → dysphagia, dyspnea, large/substernal mass
Function → symptomatic toxic nodule}

surgical indications for a thyroid nodule

toxic multinodular goiter

_{^{(decr TSH, incr T3,4)}}

-one/more nodules in multinodular goiter become TSH-independent

-NO exophthalmos/pretibial myxedema/ab’s

-Beta-blocker ± methimazole

-Radioactive iodine or surgery for definitive treatment

Older patient + hyperthyroidism + irregular multinodular thyroid + patchy radioactive iodine uptake —>

toxic adenoma

_{^{(decr TSH, incr T3,4)}}

Single autonomously functioning thyroid ‘hot’ nodule → produces thyroid hormone independent of TSH → hyperthyroidism.

-benign, no need for FNA

-Beta-blocker ± methimazole

-Radioactive iodine or surgery for definitive treatment

radioactive iodine

Used for hyperthyroidism and thyroid cancer

Absorbed by thyroid and destroys its cells

tracheoesophageal groove

the recurrent laryngeal nerve runs in this groove

hoarseness

unilateral RLN injury resluts in

Bilateral vocal cord paralysis → STRIDOR + AIRWAY OBSTRUCTION

(may require urgent intubation/tracheostomy).

bilateral recurrent laryngeal nerve injury results in

↓ PTH → HYPOCALCEMIA

(increase phosphate)

• Symptoms: Perioral/fingertip tingling, muscle cramps, tetany

• Chvostek sign: Facial twitch after tapping facial nerve

• Trousseau sign: Carpal spasm with BP cuff inflation

• Severe complications: Laryngospasm, seizures, prolonged QT, arrhythmias

note: Transient hypocalcemia is relatively common after thyroidectomy due to temporary parathyroid dysfunction; permanent hypoparathyroidism is less common.

signs of parathyroid injury from thyroid surgery

• replace the calcium:

  • Acute symptomatic treatment: IV calcium gluconate

  • Chronic treatment: Oral calcium + calcitriol

how to treat parathyroid injury from thyroid surgery

papillary = popular

most common thyroid cancer

• Orphan Annie eye nuclei → clear/empty-appearing nuclei

• Psammoma bodies → laminated calcifications

• Nuclear grooves

• Intranuclear cytoplasmic inclusions

• Papillary architecture

histology of papillary thyroid cancer

Lymphatic → cervical lymph nodes

spread of papillary thyroid cancer

Papillary thyroid ca

_Popular

_{Palpable lymph nodes}

_{Psamma bodies/ orPhan annie}

_{Prior Rad}

• Painless thyroid nodule

• Usually euthyroid → normal TSH/T3/T4

• May have painless cervical lymphadenopathy due to lymphatic spread

• Often found incidentally on imaging

• Typically occurs in younger/middle-aged adults

• History of childhood head/neck radiation is an important risk factor

• Common mutation: BRAF**; RET/PTC rearrangements can also occur.

• excellent prognosis

follicular thyroid carcinoma

A well differentiated tumor of uniform follicular cells of the thyroid gland. It is a slowly growing, painless, cold nodule.

“Flows out” - capsular/vascular invasion —> mets to lung/bone

+RAS, PAX8-PPARG rearrangements related.

good prognosis

follicular thyroid carcinoma

because ==> FNA cannot distinguish follicular adenoma from carcinoma because you must see capsular/vascular invasion → requires surgical pathology

FNA can dx all thyroid neoplasms.. except for ??

Hematogenous (bone/lung)

spread of follicular thyroid cancer

medullary thyroid cancer

“C” cells of the parafollicular cells (neuroendocrine)

+calcitonin

+congo-red staining- amyloid stroma (sheets of polygonal cells)

Cervical lymph nodes

associated w/ MEN 2A and 2B syndromes & RET mutations

{2 MEN makes C’s & RETurns}

MEN2a & MEN2b

disease associated with medullary thyroid carcinoma

• Total thyroidectomy

• Does NOT respond to radioactive iodine because C cells do not take up iodine

Major board pearl:

• Before thyroidectomy in MEN2/MTC → rule out pheochromocytoma first

• Otherwise surgery can precipitate a hypertensive crisis.

treatment of medullary thyroid carcinoma

intermediate

prognosis of medullary thyroid cancer

anaplastic thyroid cancer

Rare <1%,, MC in males >65

Local and distant METS; may invade trachea

aggressive, Poor prognosis*

tx: most are not able to be resected, chemo and radiation

THINK; OLD / FAST / DEAD = TP53 MUT.

palliative

treatment of anaplastic thyroid cancer

Thyroid Surgery — General Conduct

1. Pre-op

   • _{^{Confirm diagnosis/indication and thyroid function}}

   • _{^{Ultrasound ± FNA}}

   • _{^{Assess vocal cord function if indicated}}

   • _{^{If medullary/MEN2 → rule out pheochromocytoma FIRST ⭐}}

   • _{^{Correct significant hyperthyroidism before elective surgery}}

2. Position

   • _{^{Supine, Neck extended with shoulder roll}}

3. Incision

   • _{^{Transverse Kocher collar incision in a natural skin crease}}

4. Expose thyroid

   • _{^{Divide/retract strap muscles, Mobilize thyroid lobe}}

5. Control vessels

   • _{^{Superior thyroid vessels ligated close to thyroid → protects external branch of superior laryngeal nerve}}

   • _{^{Inferior thyroid artery branches handled carefully → preserve parathyroid blood supply}}

6. Identify & preserve ⭐⭐⭐

   • _{^{Recurrent laryngeal nerve (RLN)}}

   • _{^{External branch of superior laryngeal nerve}}

   • _{^{Parathyroid glands + their blood supply}}

7. Remove appropriate amount of thyroid → lobectomy vs total thyroidectomy ± lymph node dissection.

8. Obtain hemostasis and close.

overview of TX’s

• Papillary → surgery ± radioactive iodine; not routine chemo

• Follicular → surgery ± radioactive iodine; not routine chemo

• Medullary → surgery; NO radioactive iodine; advanced disease → targeted systemic therapy (especially RET inhibitors)

• Anaplastic → systemic therapy/targeted therapy + radiation; surgery if resectable

extra: