Chapter 22: Thyroid COPY Flashcards
1
Q
Embryology: thyroid
A
Forms from the 1st and 2nd pharyngeal arches (not from pouches)
2
Q
Released from the hypothalamaus; acts on the anterior pituitary gland and causes release of TSH
A
Thyrotropin-releasing factor (TRF)
3
Q
Released from the anterior pituitary gland; acts on the thyroid gland to release T3 and T4 (through a mechanism that involves increased cAMP)
A
Thyroid-stimulating hormone (TSH)
4
Q
What controls the release of TRF and TSH?
A
TRF and TSH release are controlled by T3 and T4 through a negative feedback loop
5
Q
1st branch off the external carotid artery
A
Superior thyroid artery
6
Q
Off thyrocervical trunk; supplies both the inferior and superior parathyroids
A
Inferior thyroid artery
7
Q
Where do you ligate the inferior thyroid artery?
A
Ligate close to thyroid to avoid injury to parathyroid glands with thyroidectomy.
8
Q
Occurs in 1%
- Arises form the innominate or aorta and goes to the isthmus
A
Ima artery
9
Q
Drain into internal jugular veins
A
Superior and middle thyroid veins
10
Q
Where do superior and middle thyroid veins drain?
A
Internal jugular vein
11
Q
Where does the inferior thyroid vein drain?
A
Innominate vein
12
Q
Nerve:
- Motor to cricothyroid muscle
- Runs lateral to thyroid lobes
- Tracks close to superior thyroid artery but is variable
- Injury results in loss of projection and easy voice fatiguability (opera singers)
A
Superior laryngeal nerve
13
Q
Nerve:
- Motor to all of larynx except cricothyroid muscle
- Runs posterior to thyroid lobes in the tracheoesophageal groove
- Can track with inferior thyroid artery but variable.
A
Recurrent laryngeal nerve
14
Q
Where does recurrent laryngeal nerve run?
A
Posterior to thyroid lobes in the tracheoesophageal groove
15
Q
Path of right vs left recurrent laryngeal nerve
A
Left RLN: loops around aorta
Right RLN: loops around innominate artery
16
Q
What can happen with injury to the recurrent laryngeal nerve?
A
Injury results in hoarseness; bilateral injury can obstruct airway -> need emergency tracheostomy
17
Q
What can happen with injury to the superior laryngeal nerve?
A
Injury results in loss of projection and easy voice fatiguability (opera singers)
18
Q
Nerve:
- Occurs in 2%
- More common on the right
A
Non-recurrent laryngeal nerve
19
Q
Nerve: risk of injury is higher for this nerve during thyroid surgery
A
Non-recurrent laryngeal nerve
20
Q
Posterior medial suspensory ligament close to recurrent laryngeal nerves; need careful dissection.
A
Ligament of Berry.
21
Q
Stores T3 and T4 in colloid
A
Thyroglobulin
22
Q
Ratio of plasma T4:T3
A
15: 1.
- T3 is the more active form (is tyrosine + iodine)
23
Q
Tyrosine + iodine
A
T3
24
Q
How is most T3 produced?
A
Most T3 is produced in the periphery from T4 to T3 conversion by deiodinases
25
Link iodine and tyrosine together
Peroxidases
26
Separate iodine from tyrosine
Deiodinases
27
Thyroid hormone transport; binds the majority of T3 and T4 in circulation
Thyroxine-binding globulin
28
Most sensitive indicator of gland function
TSH
29
Most lateral, posterior extension of thyroid tissue
| - Rotate medially to find recurrent laryngeal nerves.
Tubercles of Zuckerkandl
30
What portion of the thyroid is left behind with subtotal thyroidectomy?
Tubercles of Zuckerkandl secondary to proximity to RLNs.
| - Tubercles of Zuckerkandl: most lateral, posterior extension of thyroid tissue.
31
Produce calcitonin
Parafollicular C cells
32
Goals of thyroxine treatment
TSH levels should fall 50%
33
Long term side effect of thyroxine treatment
Osteoporosis
34
Treatment for post-thyroidectomy stridor
Open neck and remove hematoma emergently -> can result in airway compromise, can also be due to bilateral RLN injury -> would need emergent tracheostomy.
35
Symtoms: Tachycardia, fever, numbness, irritability, vomiting, diarrhea, high-output cardiac failure (MCC death)
Thyroid storm
36
MCC death in thyroid storm
High output cardiac failure
37
When is thyroid storm MC post-operatively??
MC after surgery in patient with undiagnosed Grave's disease
38
Treatment: thyroid storm
Beta-blockers, PTU, Lugol's solution (KI), cooling blankets, oxygen, glucose.
- Emergent thyroidectomy rarely indicated.
39
First line treatment of thyroid storm
Beta-blockers
40
- Very effective for thyroid storm
- Pt given high doses of iodine (Lugol's solution, potassium iodide), which inhibits TSH action on thyroid and inhibits organic coupling of iodide, resulting in less T3 and T4 release
Wolff-Chaikoff effect
41
90% of thyroid nodules are..
Benign and in females
42
Best initial test for a thyroid nodule
FNA and thyroid function tests
43
Tx: FNA shows follicular cells
Lobectomy (10% CA risk)
44
Tx: FNA shows thyroid CA
Thyroidectomy or lobectomy and appropriate treatment
45
Tx: FNA shows cyst fluid
Drain fluid.
| - If it secures or is bloody -> lobectomy
46
Tx: FNA shows colloid tissue
Most likely colloid goiter; low chance of malignancy (
47
Tx: FNA shows normal thyroid tissue and TFTs are elevate
Likely solitary toxic nodule.
| - Tx: if asymptomatic can just monitor; PTU and I(131) if symptomatic.
48
FNA: % determinate vs % indeterminate
- Determinant in 80% -> follow appropriate treatments.
| - Indeterminate in 20% -> get radionuclide study
49
If FNA is indeterminate?
Get radionuclide study.
Will show..
- Hot nodule vs Cold nodule
50
Tx: hot nodule on radionuclide study
If asymptomatic can monitor. PTU and I(131) is symptomatic.
51
Tx: cold nodule on radionuclide study
Lobectomy (more likely malignant than hot nodule)
52
Any abnormal thyroid enlargement
Goiter
53
Most identifiable cause of goiter
Iodine deficiency
| - Tx: iodine replacement
54
Diffuse thyroid enlargement without evidence of functional abnormalities
Nontoxic colloid goiter
55
When would you operate on goiter?
Unusual to have to operate unless goiter is causing airway compression or there is a suspicious nodule.
- Tx: subtotal or total thyroidectomy for symptoms or if suspicious nodule; subtotal has decreased risk of RLN injury.
56
Goiter:
- Usually secondary (vessels originate from superior and inferior thyroid arteries)
- Primary substernal goiter - rare (vessels originate from innominate artery)
Substernal goiter
57
Most likely from acquired disease with inferior extensions of a normally placed gland (e.g. substernal goiter)
Mediastinal thyroid tissue
58
- Occurs in 10%
| Extends form the isthmus toward the thymus
Pyramidal lobe
59
Thyroid tissue that persists in foramen cecum at the base of the tongue.
- S/S: dysphagia, dyspnea, dysphonia
- 2% malignancy risk
- Is the only thyroid tissue in 70% of patients who have it
Lingual thyroid
60
Tx: lingual thyroid
Thyroxine suppression, abolish with I(131)
| - Resection if worried about CA or if it does not shrink after medical therapy.
61
- Classically moves upward with swallowing
| - Susceptible to infection and may be premalignant
Thyroglossal duct cyst
Tx: resection -> need to take mid portion or all of hyoid bone alone with the thyroglossal duct cyst (Sistrunk procedure)
62
Treatment of thyroglossal duct cysts
Sistrunk procedure:
| - Resection -> take mid portion or all of hyoid bone along with the thyroglossal duct cyst.
63
Indications for propylthiouracil (PTU) and methimazole
Young patients.
Small goiters.
Mild T3 and T4 elevation.
64
- Safe in pregnancy
- Inhibits peroxidases and prevents iodine-tyrosine coupling
- Side effects: aplastic anemia, agranulocytosis (rare)
PTU (thioamides)
65
- Inhibits peroxidases and prevents iodine-tyrosine coupling
| - Side effects: cretinism in newborns (crosses placenta), aplastic anemia, agranulocytosis (rare)
Methimazole
66
- Good for patients who are poor surgical risks or unresponsive to PTU
- Do not use in children or during pregnancy -> can traverse placenta
Radioactive iodine (I-131)
67
- Good for cold nodules, toxic adenomas or multi nodular goiters not responsive to medical therapy, pregnant patients not controlled with PTU, compressive symptoms
Thyroidectomy
68
Best time to operate on thyroid during pregnancy.
2nd trimester: decreased risk of teratogenic events and premature labor.
69
Operation can leave the patient euthyroid
Subtotal thyroidectomy
70
Symptoms: women, exophthalmos, pretrial edema, atrial fibrillation, heat intolerance, thirst, increased appetite, weight loss, sweating, palpitations
Graves' disease
71
MCC hyperthyroidism (80%)
Graves' disease
72
What is the cause of Grave's disease?
Caused by IgG antibodies to TSH receptor (long-acting thyroid stimulates [LATS], thyroid-stimulating immunoglobulin [TSI])
73
Decreased TSH.
Increased T3 and T4.
LATS level.
Diffuse increase in 123-i uptake (thyroid scan).
Graves' disease
74
Tx: Graves' disease
Thioamides (50% recurrence)
131-i (5% recurrence)
Thyroidectomy if medical therapy fails.
75
Graves' disease: pre-op preparation
PTU until euthyroid. B-blocker. Lugol's solution for 14 days to decrease friability and vascularity (start only after euthyroid).
76
Graves' disease: operation
Bilateral subtotal (5% recurrence) or total thyroidectomy (need lifetime thyroxine replacement)
77
Graves' disease: indications for surgery
Noncompliant patient, reucrrence after medical therapy, children, pregnant women not controlled with PTU, or concomitant suspicious thyroid nodule
78
- Women, age > 50 years, usually nontoxic 1st
- Symptoms: tachycardia, weight loss, insomnia, airway compromise, symptoms can be precipitated by contrast dyes
- Caused by hyperplasia secondary to chronic low-grade TSH stimulation
Toxic multinodular goiter
79
Tx: toxic multinodular goiter
Most consider surgery (subtotal or total thyroidectomy) the preferred initial treatment for toxic multi nodular goiter, but a trial of i-131 should be considered, especially in the elderly and frail.
- If compression of a suspicious nodule is present, need to go with surgery
80
- Women, younger, usually > 3cm to be symptomatic, function autonomously.
Single toxic nodule
81
Dx and Tx: Single toxic nodule
Dx: thyroid scan (hot nodule) - 20% of hot nodules eventually cause symptoms
Tx: thioamides and 131-i (95% effective). lobectomy if medical treatment ineffective
82
Rare causes of hyperthyroidism
Trophoblastic tumors, TSH-secreting pituitary tumors.
83
MCC hypothyroidism in adults
Hashimoto's disease
84
- Enlarged gland, painless, chronic thyroiditis
- Women, history of childhood XRT
- Can cause thyrotoxicosis in the acute early stage
Hashimoto's disease
85
What causes Hashimotos' disease?
- Caused by both humeral and cell-mediated autoimmune disease (microsomal and thyroglobulin antibodies)
- Goiter secondary to lack of organification of trapped iodide inside gland
86
What does pathology show for Hashimoto's thyroiditis?
Pathology shows a lymphocytic infiltrate
87
Tx: Hashimotos' thryoidits
Thyroxine (first line), partial thyroidectomy if continues to grow despite thyroxine, if nodules appear, or if compression symptoms occur
88
- Usually secondary to contiguous spread
- Bacterial URI usual precursors (staph/strep)
- Normal thyroid function tests, fever, dysphagia, tenderness
Bacterial thyroiditis (rare)
89
Tx: bacterial thyroiditis
Antibiotics
- May need lobectomy to r/o CA in pts w/ unilateral swelling and tenderness.
- May need total thyroidectomy for persistent inflammation
90
- Can be a/w hyperthyroidism initially
- Viral URI precursor, tender thyroid, sore throat, mass, weakness, fatigue, women.
- Elevated ESR.
De Quervain's thyroiditis
91
Tx: De Quervain's thyroiditis
Steroids and ASA
- May need lobectomy to r/o CA in pts w/ unilateral swelling and tenderness.
- May need total thyroidectomy for persistent inflammation
92
- Woody, fibrous component that can involve adjacent strap muscles and carotid sheath
- Can resemble thyroid CA or lymphoma (need biopsy)
- Disease frequently results in hypothyroidism and compression symptoms
Riedel's fibrous struma (rare)
93
What is Riedel's fibrous struma associated with?
Sclerosing cholangitis.
Fibrotic disease.
Methysergide Tx.
Retroperitoneal fibrosis.
94
Tx: Riedel's fibrous struma
Steroids and thyroxine
- May need isthmectomy or tracheostomy for airway symptoms
- If resection needed, watch for RLNs.
95
Most common endocrine malignancy in the US
Thyroid cancer
96
% Chance of malignancy with follicular cells on FNA
5-10% chance of malignancy
97
DDx follicular cells on FNA
Follicular cell adenoma vs follicular hyperplasia vs follicular cell CA
98
Thyroid CA: characteristics with increased chance of malignancy
Solid, solitary, cold, slow growing, hard, male, age > 50, previous neck XRT, MEN 2a or 2b
99
DDx: sudden growth of thyroid cancer
Could be hemorrhage into previously undetected nodule or malignancy
100
Patients can present with voice changes or dysphagia
Think about thyroid cancer
101
- Colloid, embryonal, fetal -> no increased cancer risk.
| - Tx: still need lobectomy to prove it is an adenoma
Follicular adenoma
102
MC (85%) thyroid cancer
Papillary thyroid carcinoma
103
- Least aggressive, slow growing, has the best prognosis; women, children
- Older age (>40-50yrs) predicts a worst prognosis.
- Children are more likely to be node positive (80%) than are adults (20%)
Papillary thyroid carcinoma
104
Risk factors of papillary thyroid carcinoma
Childhood XRT (very increased risk) -> MC tumor following neck XRT
105
How do you ascertain prognosis of papillary thyroid carcinoma?
Lymphatic spread 1st but is not prognostic -> prognosis based on local invasion
106
Papillary thyroid CA: mets?
Rare - lung
107
Path: papillary thyroid CA
psammoma bodies (calcium) and Orphan Annie nuclei
108
Tx: papillary thyroid CA
- Minimal/incidental ( 1cm
- Clinically + cervical LN: need ipsilateral MRND
- Extrathyroidal tissue involvement: need ipsilateral MRND
- Mets, residual local disease, +LN, capsular invasion -> 131-i (4-6wks after surgery
- XRT only for unresectable disease not responsive to 131-i
109
When would you do total thyroidectomy for papillary thyroid carcinoma?
Bilateral lesions, multicentricity, history of XRT, positive margins, tumors > 1cm
110
Survival rate papillary thyroid CA
95% 5-year survival rate; death secondary to local disease
111
Dx: enlarged lateral neck lymph node that shows normal-appearing thyroid tissue.
Tx: ?
Dx: Papillary thyroid CA with lymphatic spread (lateral aberrant thyroid tissue)
Tx: total thyroidectomy and MRND; 131-i (4-6weeks after surgery)
112
- Hematogenous spread (bone most common) -> 50% have metastatic disease at the time of presentation.
- More aggressive than thyroid papillary cell CA; older adults (50-60s), women
Follicular thyroid carcinoma
113
What if FNA shows just follicular cells?
10% have chance of malignancy. Need lobectomy.
114
Tx: follicular thyroid carcinoma
Lobectomy -> if path shows adenoma or follicular cell hyperplasia, nothing else needed.
- Follicular CA: total thyroid for lesions > 1 or extra thyroid disease
- Clinically positive cervical nodes: ipsilateral MRND.
- Extrathyroid involvement: ipsilateral MRND.
- Lesions > 1cm or extrathyroid: 131-i (4-6 wks after surgery)
115
Survival rate follicular thyroid carcinoma
70% 5-year survival rate; prognosis based on stage
116
- Can be a/w MEN 2a, 2b (diarrhea)
- Usually the 1st manifestation of MEN 2a / 2b (diarrhea)
- Tumor arises from parafollicular C cells (which secrete calcitonin)
- C-cell hyperplasia considered premalignant
Medullary thyroid carcinoma
117
Path: medullary thyroid carcinoma
Shows amyloid deposition
118
What do you need to screen for with medullary thyroid carcinoma?
Hyperparathyroidism and pheochromocytoma.
119
Metastatic risk for medullary thyroid carcinoma
- Lymphatic spread: most have involved nodes at time of diagnosis
- Early mets to lung, liver, and bone.
120
MC site of mets in follicular thyroid carcinoma
Bone
121
Treatment: medullary thyroid carcinoma
Tx: total thyroid with central neck node dissection.
- MRND: if +nodes (bilateral MRND if both lobes have tumor) or if extra thyroidal disease present.
- XRT may be useful for unresectable local and distant metastatic disease.
122
When would you consider prophylactic thyroidectomy and central node dissection?
In medullary thyroid carcinoma.
| - in MEN 2a (at age 6 years) or 2b (at 2 years)
123
What prevents attempt at cure of medullary thyroid carcinoma?
Liver and bone metastases
124
Monitor for recurrence of medullary thyroid carcinoma
Calcitonin levels
125
Survival rate of medullary thyroid carcinoma
50% 5-year survival rate, prognosis based on presence of regional and distant metastasis.
126
- Most are benign, presents in older patients.
- Mets go to bone and lung if malignant.
- Tx?
Hurthle cell carcinoma.
| Tx: total thyroidectomy, MRND for clinically positive nodes
127
- Elderly patients with long-standing goiters
- Most aggressive thyroid CA
- Rapidly lethal, usually beyond surgical management at diagnosis.
Anaplastic thyroid cancer
128
Tx: Anaplastic thyroid carcinoma
Total thyroidectomy for the rare lesion that can be resected.
- Can perform palliative thyroidectomy for compressive symptoms or give palliative chemo-XRT
129
Survival rate anaplastic thyroid cancer
Rapidly lethal: 0% at 5-year
130
What is XRT effective for?
Papillary, follicular, medullary, and Hurthle cell thyroid CA
131
What is 131-i effective for?
Papillary and follicular thyroid CA only
132
How do you use 131-i?
- Can cure bone and lung mets
- Give 4-6 wks after surgery when TSH levels are highest.
- Do not give thyroid replacement until after treatment with 131-i -> would suppress TSH and uptake of 131-i.
133
Indications for 131-i
Used only for papillary and follicular thyroid CA
- Recurrent CA
- Primary inoperable tumors due to local invasion
- Tumors that are > 1cm or have extra thyroidal disease (extra-capsular invasion, nodal spread, or mets)
134
Why does total thyroidectomy need to be performed for patients with papillary or follicular cell CA and mets for i-131 treatment?
Need to perform total thyroidectomy to facilitate uptake of i-131 to the metastatic lesions (otherwise all gets absorbed by the thyroid gland)
135
Side effects: i-131 (rare)
Sialoadenitis, GI symptoms, infertility, bone marrow suppression, parathyroid dysfunction, leukemia
136
Can help suppress TSH an slow metastatic disease; administered only after i-131 therapy has finished
Thyroxine
137
Define the arterial blood supply to the thyroid.
1. Superior thyroid artery (first branch off external carotid)
2. Inferior thyroid artery (branch of thyrocervical trunk) (IMA artery rare)
138
What is the venous drainage of the thyroid?
1. Superior thyroid vein
2. Middle thyroid vein
3. Inferior thyroid vein
139
Name the thyroid lobe appendage coursing toward the hyoid bone from around the thyroid isthmus.
Pyramidal lobe.
140
What percentage of patients have a pyramidal lobe?
~50%.
141
What veins do your first see after opening the platysma muscle when performing a thyroidectomy?
Anterior jugular veins.
142
Name the lymph node group around the pyramidal thyroid lobe.
Delphian lymph node group.
143
What is the thyroid isthmus?
Midline tissue border between the left and right thyroid lobes.
144
Which ligament connects the thyroid to the trachea?
Ligament of Berry
145
What is the IMA artery?
Small inferior artery to the thyroid from the aorta or innominate artery
146
What percentage of patients have a IMA artery?
~3%
147
Name the most posterior extension of the lateral thyroid lobes.
Tubercle of Zuckerkandl
148
Which paired nerves must be carefully identified during a thyroidectomy?
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.
149
What other nerve is at risk during a thyroidectomy and what are the symptoms?
Superior laryngeal nerve; if damaged, patient will have a deeper and quicker voice (unable to hit high pitches)
150
What is TRH?
Thyrotropin-releasing hormone: released from hypothalamus, causes release of TSH
151
What is TSH?
Thyroid-stimulating hormone: release by the anterior pituitary; causes release of thyroid hormone from the thyroid
152
What are the thyroid hormones?
T3 and T4
153
What is the most active form of thyroid hormone?
T3
154
What is a negative feedback loop?
T3 and T4 feed back negatively on the anterior pituitary (causing decreased release of TSH in response to TRH)
155
What is the most common site of conversion of T4 to T3?
Peripheral (eg, liver)
156
What is Synthroid (levothyroxine): T3 or T4?
T4
157
What is the half-life of Synthroid (levothyroxine)?
7 days
158
What do parafollicular cells secrete?
Calcitonin
159
What percentage of people have a thyroid nodule?
~ 5%
160
What is the differential diagnosis of a thyroid nodule?
```
Multinodular goiter
Adenoma
Hyperfunctioning adenoma
Cysts
Thyroiditis
Carcinoma / lymphoma
Parathyroid carcinoma
```
161
Name three types of non thyroidal neck masses.
1. Inflammatory lesions (eg, absecess, lymphadenitis)
2. Congenital lesions (ie thyroglossal duct (midline), branchial cleft cyst (lateral)
3. Malignant lesions: lymphoma, mets, SCCa
162
What studies can be used to evaluate a thyroid nodule?
US - solid or cystic nodule
FNA
131-i: hot or cold nodule
163
What is the diagnostic test of choice for thyroid nodule?
FNA
164
What is the percentage of false negative results on FNA for thyroid nodule?
~ 5%
165
What is meant by a hot vs cold nodule?
Nodule uptake of IV 131-i or 69-mT
- Hot: increased 131-i uptake -> functioning / hyper functioning nodule
- Cold: decreased 131-i uptake -> nonfunctioning nodule
166
What are the indications for a 123-i scintiscan?
1. Nodule with multiple "non diagnostic" FNAs with low TSH
| 2. Nodule with thyrotoxicosis and low TSH
167
What is the role of thyroid suppression of a thyroid nodule?
Diagnostic and therapeutic; administration of thyroid hormone suppresses TSH secretion and up to half of the benign thyroid nodules will disappear
168
History -> suggest thyroid CA
1. Neck radiation
2. Family history (thyroid cancer, MEN2)
3. Young age (especially children)
4. Male > female
169
Signs -> suggest thyroid CA
1. Single nodule
2. Cold nodule
3. Increased calcitonin levels
4. Lymphadenopathy
5. Hard, immobile nodule
170
Symptoms -> suggest thyroid CA
1. Voice change (vocal cord paralysis)
2. Dysphagia
3. Discomfort (in neck)
4. Rapid enlargement
171
What is the MCC thyroid enlargement?
Multinodular goiter
172
What are indications for surgery with multi nodular goiter?
Cosmetic deformity, compressive symptoms, cannot r/o cancer
173
What is Plummer's disease?
Toxic multinodular goiter
174
What % of cold thyroid nodules are malignant?
~ 25% in adults
175
What % of multi nodular masses are malignant?
~ 1%
176
What is the treatment of a patient with a h/o radiation exposure, thyroid nodule, and negative FNA?
Most experts would remove the nodule surgically (Because of the high risk of radiation)
177
What should be done with thyroid cyst aspirate?
Send to cytopathology
178
Name the FIVE main types of thyroid carcinoma and their relative percentages.
1. Papillary: 80%
2. Follicular: 10%
3. Medullary: 5%
4. Hurthle cell: 4%
5. Anaplastic: 1-2%
179
What are the s/s thyroid CA?
Mass / nodule, lymphadenopathy, most are euthyroid
180
What comprises the thyroid CA work up?
FNA, thyroid U/S, TSH, calcium level, CXR, +/- scintiscan 123-i
181
What oncogenes are associated with thyroid cancers?
Ras gene family and RET porto-oncogene.
182
What is papillary carcinoma's claim to fame?
MC thyroid cancer - 80% of all thyroid cancers
183
Environmental risk: papillary CA
radiation exposure
184
Average age: papillary CA
30-40 years
185
Sex distribution: papillary CA
Female > male - 2:1
186
Associated histologic findings: papillary CA
Psammoma bodies
187
Describe the route and spread - papillary CA
Most spread via lymphatics (cervical adenopathy); occurs slowly
188
papillary CA: i-131 uptake
Good uptake
189
What is the 10-year survival rate of papillary CA?
~ 95%
190
What is the treatment for
1. Thyroid lobectomy and isthmectomy
2. Near-total thyroidectomy
3. Total thyroidectomy
191
What is the treatment for papillary CA > 1.5 cm, bilateral, + cervical node mets, OR a h/o radiation exposure?
Total thyroidectomy
192
Does positive cervical nodes affect prognosis of papillary CA?
No!
193
What is the treatment for lateral palpable cervical lymph nodes in papillary CA?
Modified neck dissection (ipsilateral)
194
What is the treatment for central cervical lymph nodes of papillary CA?
Central neck dissection
195
What is a "lateral aberrant thyroid" in papillary cancer?
Misnomer - it is metastatic papillary carcinoma to a LN
196
What post op med should be administered in papillary CA?
Thyroid hormone replacement, to suppress TSH
197
What is the postoperative treatment option for papillary carcinoma?
Post op 131-i scan can locate residual tumor and distant mets that can be treated with ablative doses of 131-i.
198
What is the MC site of distant mets in papillary CA?
Pulmonary (lungs)
199
What are the "P's" of papillary CA?
Popular. Psammoma bodies. Palpable lymph nodes. Positive 131-i uptake. Positive prognosis. Postop 131-i scan. Pulmonary mets.
200
What percentage of thyroid cancers is follicular CA?
~ 10%
201
Describe the nodule consistency of follicular CA?
Rubbery, encapsulated
202
What is the route of spread of follicular CA??
Hematogenous, more aggressive than papillary adenocarcinoma
203
What is the male:female ratio of follicular CA?
1:3
204
131-i uptake follicular CA?
Good uptake
205
What is the overall 10-year survival rate follicular CA?
~ 55%
206
Can the diagnosis of follicular CA be made by FNA?
No; tissue structure is needed for the diagnosis of cancer.
207
What histologic findings describe malignancy in follicular CA?
Capsular or blood vessel incasion
208
What is the MC site of distant mets of follicular CA?
Bone
209
What is the treatment of follicular CA?
Total thyroidectomy
210
What is the post op treatment option of follicular CA?
Post op 131-i scan for diagnosis / treatment
211
What are the four F's of follicular cancer?
Far-away mets (spreads hematogenously)
Female (3:1 ratio)
FNA
Favorable prognosis
212
What is hurthle cell thyroid Ca?
Thyroid cancer of hurthle cells
213
What percentage of thyroid cancers is hurthle cell thyroid Ca?
~ 5%
214
What is the cell of origin of Hurthle cell?
Follicular cells
215
131-i uptake in hurthle cell ca?
No uptake
216
How is the diagnosis of hurthle cell ca made?
FNA can identify cells, but malignancy can be determined only by tissue histology (like follicular cancer)
217
What is the route of metastasis of hurthle cell ca?
Lymphatic > hematogenous
218
What is the treatment of hurthle cell ca?
Total thyroidectomy
219
What is the 10-year survival rate of hurthle cell ca?
80%
220
What percentage of all thyroid cancers does medullary carcinoma comprise?
~ 5%
221
With what other conditions is medullary carcinoma associated?
MEN type 2; autosomal-dominant genetic transmission
222
Histology of medullary carcinoma?
Amyloid
223
What is the tumor marker of medullary carcinoma?
Calcitonin
224
What is the appropriate stimulation test for medullary carcinoma?
Pentagastrin (causes an increase in calcitonin)
225
Describe the route of spread of medullary carcinoma
Lymphatic and hematogenous distant mets
226
How is the diagnosis of medullary carcinoma made?
FNA
227
131-i uptake medullary carcinoma
Poor uptake
228
What is the associated genetic mutation of medullary carcinoma
RET proto-oncogene
229
What is the female/male ratio of medullary carcinoma?
Female > male; 1.5:1
230
What is the 10-year survival rate of medullary carcinoma?
80% without LN involvement. 45% with LN spread.
231
What should all patients with medullary thyroid cancer also be screened for?
MEN2: pheochromocytoma, hyperparathyroidism
232
If medullary carcinoma and pheochromocytoma are found, which one is operated on first?
Pheochromocytoma
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What is the treatment of medullary carcinoma?
Total thyroidectomy and median lymph node dissection. Modified neck dissection, if lateral cervical nodes are positive.
234
What are the M's of medullary carcinoma?
MEN II
Amyloid
Median lymph node dissection
Modified neck dissection if lateral nodes are positive
235
What is anaplastic carcinoma is also known as?
Undifferentiated carcinoma
236
What is anaplastic carcinoma?
Undifferentiated cancer arising in ~ 75% of previously differentiated thyroid cancers (MC'ly, follicular carcinoma)
237
What percentage of all thyroid cancers does anaplastic carcinoma comprise?
~ 2%
238
What is the gender preference of anaplastic carcinoma?
Women > Men
239
What are the associated histologic findings of anaplastic carcinoma?
Giant cells, spindle cells
240
131-i uptake of anaplastic carcinoma?
Very poor uptake
241
How is the diagnosis made of anaplastic carcinoma?
FNA (large tumor)
242
What is the major differential diagnosis of anaplastic carcinoma?
Thyroid lymphoma (much better prognosis)
243
What is the treatment of the following disorders: small tumors of anaplastic carcinoma?
Total thyroidectomy + XRT / chemotherapy
244
What is the treatment of airway compromise of anaplastic carcinoma?
Debulking surgery and tracheostomy, XRT/chemotherapy
245
What is the prognosis of anaplastic carcinoma?
Dismal, because most patients are at stage IV at presentation (3% alive at 5 years)
246
What lab value must be followed postoperatively after a thyroidectomy?
Calcium decreased secondary to parathyroid damage; during lobectomy, the parathyroids must be spared and their blood supply protected; if blood supply is compromised intraoperatively, they can be autographed into the SCM or forearm
247
What is the differential diagnosis of postoperative dyspnea after a thyroidectomy?
- Neck hematoma (remove sutures and clot at the bedside).
| - Bilateral recurrent laryngeal nerve damage
248
What is a "lateral aberrant rest" of the thyroid?
Misnomer: it is papillary cancer of a lymph node from metastasis
249
What is the MCC hyperthyroidism?
Graves' disease
250
What is Graves' disease?
Diffuse goiter with hyperthyroidism, exophthalmos, and pretibial myxedema
251
What is the etiology of Graves'?
Caused by circulating antibodies that stimulate TSH receptor on follicular cells of the thyroid and cause deregulated production of thyroid hormones (i.e., hyperthyroidism)
252
What is the female: male ratio of graves' disease?
6:1
253
What specific physical finding is a/w Graves'?
Exophthalmos
254
How is the diagnosis made of Graves'?
Increased T3, T4, and anti-TSH receptor antibodies, decreasedTSH, global uptake of 131-i radionuclide
255
Name treatment option modalities for Graves' disease.
1. Medical blockade: iodide, propranolol, PTU, methimazole, Lugol's solution
2. Radioiodide ablation: most popular therapy
3. Surgical resection: bilateral subtotal thyroidectomy
256
What are the possible indications for surgical resection of Graves' disease?
Suspicious nodule; if patient is noncompliant or refractory to medicines, pregnant, a child, or if patient refuses radio iodide therapy.
257
What is the major complication of radio iodide or surgery for Graves' disease?
Hypothyroidism
258
What does PTU stand for?
Propylthiouracil
259
How does PTU work?
1. Inhibits incorporation of iodine into T4/T3 (by blocking peroxidase oxidation of iodine to iodine)
2. Inhibits peripheral conversion of T4 to T3
260
How does methimazole work?
Inhibits incorporation of iodine into T4/T3 only (by blocking peroxidase oxidation of iodine to iodine)
261
What is toxic multi nodular goiter?
Plummer's disease
262
What is toxic multi nodular goiter?
Multiple thyroid nodules with one or more nodules producing thyroid hormone, resulting in hyper functioning thyroid (hyperthyroidism or a "toxic" thyroid state)
263
What medication may bring on hyperthyrdoisim with a multi nodular goiter?
Amiodarone (or any iodine-containing medication / contrast)
264
How is the hyper functioning thyroid nodule localized?
131-i radionuclide scan
265
What is the treatment of toxic multi nodular goiter?
Surgically remove hyper functioning nodules with lobectomy or near total thyroidectomy
266
What is Pemberton's sign?
Large goiter causes plethora of head with raising of both arms.
267
What are the features of acute thyroiditis?
Painful, swollen thyroid, fever, overlying skin erythema, dysphagia
268
What is the cause of acute thyroiditis?
Bacteria (usually Streptococcus or Staphylococcus), usually caused by a thyroglossal fistula or anatomic variant
269
What is the treatment of acute thyroiditis?
Antibiotics, drainage of abscess, needle aspiration for culture, most patients need definitive surgery later to remove the fistula.
270
What are the features of subacute thyroiditis?
Glandular swelling, tenderness, often follows URI, elevated ESR
271
What is the cause of subacute thyroiditis?
Viral infection
272
What is De Quervain's thyroiditis?
Another name for subacute thyroiditis
273
How can the difference between the etiologies of acute and subacute thyroiditis be remembered?
A before S, B before V. (Acute before Subacute, Bacterial before Viral. (Acute: bacterial, Subacute: viral)
274
What are the common causative bacteria in acute suppurative thyroiditis?
Streptococcus or Staphylococcus
275
What are the two types of chronic thyroiditis?
1. Hashimoto's thyroiditis
| 2. Reidel's thyroidits
276
What are the features of Hashimoto's (chronic) thyroiditis?
Fine and rubbery gland, 95% in women, lymphocyte invasion.
277
What is the claim to fame of Hashimoto's disease?
MCC hypothyroidism in the US
278
What is the etiology of Hashimoto's disease?
Autoimmune
279
What lab tests should be performed to diagnose Hashimoto's disease?
Antithyroglublin and microsomal antibodies
280
What is the medical treatment for Hashimoto's thyroiditis?
Thyroid hormone replacement if hypothyroid (surgery is reserved for compressive symptoms and/or if cancer needs to be ruled out)
281
What is Riedel's thyroiditis?
Benign inflammatory thyroid enlargement with fibrosis of the thyroid. Patients present with painless, large thyroid. Fibrosis may involve surrounding tissues.
282
What is the treatment for Riedel's thyroiditis?
Surgical tracheal decompression, thyroid hormone replacement as needed - possibly steroids / tamoxifen if refractory.
