Chapter 15 - Thyroid, Parathyroid Flashcards by Ben Walters

How many thyroid nodules found on PET will be found to be malignant?

As many as 2/3

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Initial workup of palpable thyroid nodule

U/S
Laryngoscopy
Thyroid function assay, calcium

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Most common malignancy of thyroid

PTC

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Most common neoplasm of thyroid

follicular adenoma

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Percentage of pop with thyroid nodules palpable

Percentage of these that are cancer (and things that increase risk)

4-7%
5-10%
<30 >60, male, FHx, rads as child, high TSH/Hashimoto, rapid grow, pain, compression sx, hoarse, cervical LAD

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What features on U/S make you FNA a nodule?

>1cm OR:
microcalcification
irregular margin
solid (not cystic)
internal vascularity
multiple nodules
ipsilateral cervical LAD

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Diagnostic accuracy of FNA

95%
False neg 2.3%
False pos 1.1%

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TIRADS Classification (u/s)

1- NL
2- Benign (simple cyst, spongiform nodule, isolated macrocalcify, subacute thyroiditis). 3- Probably benign (isoechogenic, hyperechogenic)
4A- low suspicion (moderately hypoechogenic)
4B- 1-2 high risk signs and no adenopathy
5- 3+ signs and/or adenopathy. >80% risk malignant
High risk Signs: Taller than wide, irregular/microlobulated margins, microcalcify, marked hypoechogenicity
6- Biopsy proven malignancy

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FNA reporting of thyroid. Classification

Benign - 70%
Malignant - 5%
Suspicious- 10%
Indeterminate- 15%

10-20% of suspicious will be follicular CA
May do molecular testing on indeterminate (Mutation panel, gene expression testing)

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Mutation panel testing for thyroid cancer, and gene expression testing

100% PPV (rule in), but 30% don’t have a mutation
RAS, PPARg, RET/PTC, BRAF

GET: 142 genes, rules out, NPV >95%, $3,000

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How to follow benign nodule

Serial u/s q6-12 mo
repeat FNA if significant change
If cysts return after multiple FNA, consider removal

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Percentage of occurrence of all thyroid CA

PTC 70-85%
Foll CA 15-20%
Huerthle 2-5%
MTC 3-10%
Anaplastic <2%
Insular/poorly differentiated (rare)
Lymphoma, SCC, mets

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T Staging thyroid CA

T1a 1cm
1b 1-2cm
T2 2-4cm
T3 >4cm
4a: to ST, larynx, trachea, esophagus, RLN
4b: beyond above regions

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N Staging thyroid

1a- spread to central (pretracheal, paratracheal, prelaryngeal)
1b- beyond central

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Staging of PTC or FTC <45 yo

I: Anything less than M1
II: M1

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Staging of PTC, FTC >45 yo

I: T1
II: T2-3
III: T4 or N1a
IVa: 4a, or N1b
IVb: 4b
IVc: M1

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Low risk prognosis for thyroid cancer (AMES)

Age <40/50 (m/f), tumor <4cm, within thyroid

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High risk prognosis thyroid: AMES and MACIS

Age >41/51 (m/f), extrathyroid, >5cm

Age >40, invasion of gland, incomplete resection, >4cm

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Near total vs sub-total thyroidectomy

Near: leave SMALL amount thyroid tissue around parathyroids, RLN to reduce morbidity
Sub: large amounts of thyroid left

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Treatment of Stage I-II PTC, Foll CA?

Total thyroidectomy

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Treatment Stage III PTC, FTC

Total thyroid plus removal of involved LN/other sites of thyroid dz
I-131 ablate if demonstrates uptake, or external beam rads if I-131 uptake is minimal

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Treatment Stage IV PTC, FTC

total thyroid, neck
Ablate with I-131 or Rads or chemo (VEGF inh)
May remove mets with no I-131 uptake

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Which thyroid CA does not spread to LN often?

Follicular

Papillary and Medullary do, eval central and II-IV, some authors say do central if PTC >3cm

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MEN I, IIa, IIb

I- para, pit, panc
IIa- MTC, pheo, para (RET)
IIb- MTC, pheo, mucosal neuromas (RET), most aggressive medullary

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How does medullary behave differently?

Aggressive Secrete calcitonin, CEA, prostaglandin, serotonin, histaminase Incades muscle, trachea, heme spread to lungs/viscera (50% @ pres) 30% are familial/genetic

How to screen for Pheo

All patients with medullary get RET testing | If positive, do 24 hr urine catecholamine, abdominal scan

How to screen for parathyroid adenoma

serum calcium, PTH | Sestamibi

Imaging workup in patients with medullary

MRI, PET, sestamibi, indium-labeled somatostatin scans

Treatment and f/u for medullary

total thyroid plus other involved areas | f/u calcitonin, CEA

Describe anaplastic thyroid CA

80% occur in pre-existing mass Sudden growth, pain, hoarse, dysphagia, dyspnea All are stage IV (a to nearby, b beyond nearby, c mets)

Treatment and survival of anaplastic

Median survival less than 6 mo | Doxorubicin, Rads, debulking surg, trach

What to consider when deciding to do RAI

Size, lymphovascular invasion, invade thyroid capsule, LN

Thyroid cancer recurrence statistics

10-30% recur/metastasize 80% recurrences in neck alone (otherwise lungs) 50% cured with second operation If recur by I-131 and not clinically apparent, good prognosis, Tx with I-131 Multi-tyrosine kinase INH if not resp to I-131

How many have 5-7 parathyroid glands? And fewer than 4?

3-7% | 3-5%

Average weight of parathyroid, diameter, blood supply

35-50 mcg 1-5mm ITA (rarely posterior br STA)

Causes of primary hyperpara

solitary adenoma (85%) multiple hyperplastic glands (10-15%) multiple adenomas (3-4%) carcinoma (<1%) Overexpression PRAD1 oncogene, low-dose rads exposure may be responsible

Secondary and tertiary hyperpara

2: CRF, Surg if osteopenia (3 1/2 removal), May use cinacalcet 3: autonomous para

Sx of hypercalcemia

``` GI- nausea, constip, ulcer, pancreatitis Mm weak Stones HTN, arrhythmia Polydipsia Depress, tired, memory ```

DDx hyperCa

``` Mets from BLTKP MM SCLC, ovarian, thymoma Gloma Thiazides, lithium, theophylline, hypervit A/D Immobile Milk-Alkali Fam Hypocalciuric hyperCa Hyperphosphatasia Pagets ```

Elevated PTH but normal calcium - causes

Vitamin D Insuff | Malabsorption

Imaging options for primary hyperpara

T99 sestamibi - to mitochondria, 2 hours later out of thyroid. 100 Se 90 Sp ``` T99 MIBI SPECT-3D T99 thallium subtraction U/S, FP 15-20% MRI (T2) Intraop gamma Angiography Venous sample FNA ```

Ectopic para locations

Sup Med, thymic capsule, retro-esoph, carotid sheath, medial to sup thyroid pole Sup para usually near lateral lobe. Inferior more variable

When to perform surgery in asymptomatic primary hyperpara

``` Serum Ca 1 above NL GFR <60 T score <2.5 or prior fx/fragile <50 Patient wants surgery, cannot be reliably followed ```

Intraop PTH monitoring

1/2 life 3-5 min | Want see decrease by 50% 10 min after removal of adenoma/hyperplasia

Autotransplant para

Immediate or up to 18 mo frozen SCM, brachioradialis Fxn within 3 m, success rate 50% Arm: can remove under local if hyperplasia

When could it be appropriate to do lobectomy for thyroid CA

<1cm low risk papillary CA | 5-10% recur c/l

When to not do RAI, risks of RAI

No benefit if complete resection, no nodes, T1-2, >45 Second CA, Sialadenitis, Lacrimal, Salivary Dysfxn Give with rhTSH to decrease risk

Parathyroid re-exploration

``` SCM to retroesoph Thymus PVS Thyroid lobe palpate Open sheath hyoid to mediastinum Explore Sup Mediastinum ```

Which cancers go to 1a?

Oral tongue, FOM, lower gum/lip

Which cancers go to 1b?

OC (buccal, tongue, lateral FOM) Anterior nasal cavity Max sinus SM gl

Which cancers go to 2?

OC, nose, NP, OP, HP, larynx, parotid

Which cancers go to 3?

OC, OP, NP, HP, larynx

Which cancers go to 4?

HP, thyroid, larynx, esophagus

Which cancers go to 5?

Skin post scalp/neck, NP, OP

Which cancers go to 6?

Thyroid, larynx (glott, subglott), esophagus, piriform sinus apex

Nasopharyngeal nodal staging

1: unilat, <6cm, above supraclav 2: bilat 3: >6 or to supraclavicular fossa (b)

Deficit from injured XI

Can’t raise shoulder above 90 degrees, shoulder pain

If need to remove both IJ, how long do you wait?

2 weeks to remove second one 10% die when simultaneous

Which neck dissection to do for: OC

1-3

Which neck dissection to do for: OP, HP, Lar

2-4 (Lat)

Which neck dissection to do for: post scalp

2-5, retroauric, Suboccip (PL neck diss)

Which neck dissection to do for: Ant/lat face

1-3, parotid, facial

Which neck dissection to do for: Thyroid, esoph, advanced laryngeal

Chyle Leak

Occurs 1-2% Duct enters IJ sup to jxn with subclavian Surgery if >500cc/day (May do TPN instead) Less- pressure dressing, low fat diet, drainage

Cause of SIADH after IJ ligation

Cerebral edema

Which patients are at risk for facial/cerebral edema after ND?

Prior Rads, IJ ligation

Things that INC risk of carotid blowout

``` Salivary fistula Flap breakdown (prior Rads) Malnutrition, Infxn, diabetes ```

When to do neck dissection along with chemo Rads

N2b/3 N1-2 and persistent nodal Disease 3mo after Tx

When to do open biopsy rather than FNA for suspected cancer in node

Only if suspected lymphoma

Sacrifice carotid?

If you assess COW collaterals (balloon occlusion, xenon inhalation CT) then CNS compl 12%, 1 year disease free survival 45%, 2 year 22%.

When to consider postop radiation

ECS, multiple positive nodes

When to do MRND for salvage rather than SND

Fixate, infiltrate surrounding tissue from nodal Mets