Thyroid Nodules and Thyroid Cancer Flashcards by Jane Keery

Are thyroid nodules mostly benign or malignant?

Benign

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What two features are suggestive of the nodule being within the thyroid?

It moves on swallowing

- It is painless

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If a nodule is in the thyroid, what type of fascia will it be invested in?

Pretrachial fascia

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When will a thyroid nodule be painful?

If a cyst has formed which is bleeding and expanding

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What are the two most important questions in a history of a thyroid nodule?

Has there been neck irradiation?

- Is there a family history of thyroid cancer?

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What are two important things to look/assess for on examination of a thyroid nodule?

Lymphadenopathy in the neck

- Hoarseness of the voice

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If lymph nodes are found in the neck along with a thyroid nodule, what is this until proven otherwise?

Papillary thyroid cancer

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What is hoarseness of the voice suggestive of?

Recurrent laryngeal nerve palsy- an aggressive cancer

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What are the most important investigations for a thyroid nodule?

TSH levels

- US and FNA

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What are the different FNA/US stages and what does each signify?

Thy1- inadequate
Thy2/U2- benign
Thy3 (a/f)/U3- atypical
Thy4/U4- probably malignant
Thy5/U5- malignant

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Thy3a FNA staging has what % chance of being malignant?

30%

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Where do most thyroid tumours arise from?

Follicular cells

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What is the most common tumour of the thyroid?

Follicular adenoma

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What type of tumours are follicular adenomas?

Benign, glandular

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Follicular adenomas are encapsulated. What does this mean?

They are surrounded by a band of collagen within which there are closely packed thyroid follicles

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Are follicular adenomas functioning or non-functioning?

Normally non-functioning but can sometimes secrete thyroid hormones

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If a follicular adenoma was to secrete thyroid hormones, is this TSH dependent or independent?

TSH independent

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What genetic mutations are associated with follicular adenoma?

Ras oncogene

TSHR signalling pathway

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As well as follicular adenoma, what are some other causes of a benign solitary nodule?

Cyst
Colloid nodules
Hyperplastic nodules

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Most thyroid cancers are what type?

Carcinomas

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What are carcinomas?

Malignant epithelial tissue

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Which types of thyroid carcinomas can be differentiated?

Papillary and follicular

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What thyroid carcinoma is the most common?

Papillary

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What does it mean for a cancer to be differentiated?

They look and behave very similarly to normal cells

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What is the main advantage and main disadvantage of differentiated cancer?

D: can be hard to spot/diagnose A: very good prognosis

Most differentiated cancers take up X, secrete Y and are Z driven?

``` X= iodine Y= thyroglobulin Z= TSH ```

Which sex is more commonly affected by thyroid cancers?

Females

How do the rates of thyroid cancer vary with age in both men and women?

Women- rates increase from age 15-40 and then plateau | Men- rate steadily increases with age

Thyroid cancers have a lower incidence in what race?

Afro-Americans

Thyroid cancers have a strong association with what environmental factor?

Exposure to radiation

How soon after a nuclear incident do effects start to show?

Exactly 25 years

What 3 things does thyroid cancer have a weak association with?

- Thyroid adenoma - Chronic elevation of TSH - More children a woman has had

What factors does thyroid cancer have NO association with, that are common risk factors for other cancers?

Diet, other malignancies, smoking

What do most thyroid cancer patients present with?

A palpable nodule, most likely to be an enlarged lymph node

A pathological fracture is most likely to be caused by what type of thyroid cancer?

Follicular

How does papillary cancer tend to spread? This makes what a common presentation?

Spreads via lymphatics- cervical lymphadenopathy is a common presentation

Does cervical lymphadenopathy with papillary thyroid cancer alter the prognosis?

If papillary cancer was to spread haematogenously, where are some areas it may spread to?

- Bones - Liver - Lungs - Brain

What two factors is papillary thyroid cancer associated with?

Hashimoto's thyroiditis and ionising radiation

What is the prognosis for papillary and follicular differentiated cancer?

10 year mortality < 5%

What are some local effects of papillary thyroid cancer?

Hoarseness, dysphagia, cough, dyspnoea

What age group does papillary thyroid cancer tend to affect?

30-40

What genetic features are associated with papillary thyroid cancer?

BRAF and RAS mutations

What type of nuclei is seen in papillary thyroid cancer?

Orphan Annie eye- clear and grooved

How does follicular cancer tend to spread? This makes what more common?

Haematogenously, making distal metastases more common

What is the peak age for follicular cancer?

Around 50

What are some genetic features associated with follicular thyroid cancer?

Mutations in P13k/AKT pathways or the RAS family

Most follicular thyroid cancer patients present with what FNA score?

Thy3f

Can you tell if there has been capsular invasion with an FNA?

When a new thyroid nodule presents, what are some clinical indicators of malignancy?

- New nodule aged < 20 or > 50 - Increasing in size - > 4cm diameter - History of head/neck irradiation - Vocal cord palsy

What investigation is most effective at showing lymph nodes? What should be done if these are found?

Ultrasound- should be taken out completely

What investigation should be performed if there is a suspected vocal cord palsy?

Pre-operative laryngoscopy

What investigations are there no role for in thyroid cancer?

Isotope scans, CT, MRI

What are some features of a low risk group?

< 40 No metastases Cancer confined to the thyroid

What are some features of a high risk group?

Age > 40 | Any metastases

What do T1/2/3 mean in TNM staging of thyroid cancer?

T1- size 2cm or less T2- size greater than 2cm up to 4cm (limited to thyroid) T3- size greater than 4cm , limited to the thyroid or with minimal extension

What do T4a and T4b in TNM staging of thyroid cancer?

T4a- moderately advanced disease, tumour extending beyond the capsule to subcutaneous tissues T4b- very advanced disease, tumour invades pre vertebral fascia or vessels

What do N0 and N1 mean in TNM staging of thyroid cancer?

N0- no regional node metastases | N1- regional node metastases

What do N1a and N1b mean in TNM staging of thyroid cancer?

N1a- metastases to level VI (pre tracheal, paratracheal or pre laryngeal nodes) N1b- metastases to unilateral, bilateral or contralateral cervical, retropharyngeal or superior mediastinal nodes

What do M0 and M1 mean in TNM staging of thyroid cancer?

M0- no metastases | M1- distal metastases present

What level of the neck are thyroid cancers mostly seen?

Levels 3/4

What is the treatment of choice for thyroid cancers?

Surgery

What are the pros and cons of a lobectomy?

Less invasive and lower morbidity | The other lobe is then prone to cancer and investigations are difficult

When are lobectomies used?

Very low risk patients

What is the deal with Ca++ and post-operative care after a thyroidectomy?

Ca++ checked in first 24 hours | Ca++ replaced if < 2mmol/l (IV if < 1.8mmol/l or the patient is symptomatic)

What test is performed 3-6 months post-op of a thyroidectomy?

Whole body iodine scanning

What must happen to T3 and T4 treatment before a patient undergoes a whole body iodine scan?

T4 stopped 4 weeks before | T3 stopped 2 weeks before

What is used as a tumour marker for differentiated cancer?

Thyroglobulin

How can you get rid of any leftover thyroid tissue following a thyroidectomy?

Thyroid remnant ablation

What are some side effects of thyroid remnant ablation?

Sialadenitis, sore throat, increased risk of acute myeloid leukaemia

Does thyroid remnant ablation have any effect on increased incidence of other tumours, infertility or genetic abnormalities of offspring?

After completion of therapy and follow up for thyroid cancer, patients are maintained on X therapy, with the aim of suppressing TSH to Y and have a fT4 level of Z?

``` X= T4 Y= < 0.1 U/l Z= < 25 ```

How can recurrent disease be detected?

Rising thyroglobulin or imaging

Recurrence in cervical lymph nodes is mostly seen in what cancer?

Papillary

Recurrence to distal sites is mostly seen in what cancer?

Follicular

Recurrent disease is seen within how long of the first cancer?

2 years

What is the recurrence rate for differentiated thyroid cancer? Are these treated successfully?

30%- with most being treated successfully

If thyroglobulin is rising but there is a negative whole body iodine scan, what test could be done?

PET

What can be used as a tumour marker for medullary thyroid carcinoma?

Calcitonin

What type of tumours are medullary thyroid carcinomas? Where are they derived from and what do they secrete?

Neuroendocrine- derived from C-cells (parafollicular) and secrete calcitonin

What genetic factor is related to medullary thyroid cancer?

MENIIa and MENIIb, familial medullary carcinoma

What should always be checked when there is a medullary thyroid cancer with suspicion of MEN?

24h urinary metanephines and genetics | Screen family

Medullary thyroid cancer is associated with deposition of what? What does this represent?

Amyloid deposition- represents abnormally folded calcitonin

Who does anaplastic thyroid carcinoma occur in?

Older patients, maybe with a PMH of differentiated thyroid cancer

What genetic factors are involved in anaplastic thyroid cancer?

p53 and B-catenin mutations

Who does thyroid lymphoma occur in?

Those with a background of autoimmune hypothyroidism on T4