Thyroid Nodules and Thyroid Cancer Flashcards
Are thyroid nodules mostly benign or malignant?
Benign
What two features are suggestive of the nodule being within the thyroid?
- It moves on swallowing
- It is painless
If a nodule is in the thyroid, what type of fascia will it be invested in?
Pretrachial fascia
When will a thyroid nodule be painful?
If a cyst has formed which is bleeding and expanding
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?
What are two important things to look/assess for on examination of a thyroid nodule?
- Lymphadenopathy in the neck
- Hoarseness of the voice
If lymph nodes are found in the neck along with a thyroid nodule, what is this until proven otherwise?
Papillary thyroid cancer
What is hoarseness of the voice suggestive of?
Recurrent laryngeal nerve palsy- an aggressive cancer
What are the most important investigations for a thyroid nodule?
- TSH levels
- US and FNA
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
Thy3a FNA staging has what % chance of being malignant?
30%
Where do most thyroid tumours arise from?
Follicular cells
What is the most common tumour of the thyroid?
Follicular adenoma
What type of tumours are follicular adenomas?
Benign, glandular
Follicular adenomas are encapsulated. What does this mean?
They are surrounded by a band of collagen within which there are closely packed thyroid follicles
Are follicular adenomas functioning or non-functioning?
Normally non-functioning but can sometimes secrete thyroid hormones
If a follicular adenoma was to secrete thyroid hormones, is this TSH dependent or independent?
TSH independent
What genetic mutations are associated with follicular adenoma?
Ras oncogene
TSHR signalling pathway
As well as follicular adenoma, what are some other causes of a benign solitary nodule?
- Cyst
- Colloid nodules
- Hyperplastic nodules
Most thyroid cancers are what type?
Carcinomas
What are carcinomas?
Malignant epithelial tissue
Which types of thyroid carcinomas can be differentiated?
Papillary and follicular
What thyroid carcinoma is the most common?
Papillary
What does it mean for a cancer to be differentiated?
They look and behave very similarly to normal cells
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?
No
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?
No
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?
No
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