Thyroid/Neck lumps Flashcards
What is a goitre?
Any enlargement of the thyroid gland. Most often due to lack of dietary iodine
What TFT results would you expect in low dietary iodine?
reduced fT3/4 production & high TSH (-> gland enlargement)
List some substances that limit T3/4 production.
broccoli, cauliflower, cabbage
lithium, amiodarone
Who would typically present with a diffuse goitre?
sporadic; F>M, puberty & young adults.
usually present with cosmetic issue since usually euthyroid
what TFTs would you expect for a sporadic diffuse goitre?
T3/4 normal but TSH high/upper limit normal
What developmental condition can result in babies if they have dyshormonogenesis relating to thyroid hormones?
cretinism - absence of T4 after 3months -> permanent developmental delay
What cellular disruption would you see in a multi-nodular goitre?
rupture of follicles, haemorrhage, scarring, calcification
A patient presents with a discrete solitary mass that they reckon they have had for a while now but have only noticed recently since they have been having trouble swallowing. Differentials?
Follicular Adenoma
Dominant nodule in a multi-nodular goitre
Follicular carcinoma
Describe the architecture of a follicular adenoma.
encapsulated by a surrounding collagen cuff
composed of neoplastic thyroid follicles (i.e. follicular adenoma)
What is a Differentiated Thyroid Cancer?
Differentiated refers to histological appearance but also physiological characteristic:
most take up Iodine and secrete thyroglobulin
DTCs are TSH driven
if ‘differentiated’ features = good prognosis compared to other solid tumours (i.e. anaplastic)
Who typically gets DTC?
uncommon in children
F: rates increased from 15-40 but plateau
M: steady increase with age
DTC are associated with diet, smoking, other proven malignancies, FH… true or false?
false - only strong assoc. is radiation exposure
Name the types of DTCs
papillary
follicular
medullary
How does papillary DTC spread?
via lymphatics
haematogenous spread uncommon but if it does happen -> lungs
Describe a papillary DTC (key features) and its prognosis.
usually solitary nodule, often cystic, may be calcifications in cytoplasm (psammoma bodies) and enlarged nuclei with clear centres + dark edges = Orphan Annie nuclei
good prognosis
Papillary thyroid cancer is associated with Grave’s disease. True or false?
false - associated with Hashimoto’s thyroiditis
How might a papillary DTC present?
lesion in thyroid gland or cervical lymph node
hoarseness, dysphagia, cough, dyspnoea
if PC is lymph node mets & thyroid tissue / psammoma body in lymph node -> search for occult papillary carcinoma
What is the 2nd commonest DTC and who gets it?
Follicular carcinoma
F>M; older age group than papillary (40-50s)
incidence slight raised in areas of iodine deficiency
Describe a Follicular DTC and how it spreads.
usually single nodule - slowly enlarging, painless, non-functional
haematogenous spread; lymphatic spread rare THEREFORE no lymph node enlargement
Describe the types of growth pattern of follicular DTC.
Widely invasive: more solid architecture, less follicular architecture, more mitotic activity
Minimally invasive: follicular architecture (= well-differentiated), may have surrounding capsule
How do you differentiate a follicular adenoma from a follicular carcinoma if they both have follicular architecture?
carcinoma will have vascular/capsular invasion, adenoma will not
Name the DTC that is a neuroendocrine tumour and list its associations.
Medullary thyroid cancer (MTC) arises from C-cells (calcitonin cells) 70% sporadic assoc. with MEN 2A or 2B familial medullary carcinoma
Describe a typical patient MTC patient with MEN2A/B / a familial case
very young patient - most have prophylactic thyroidectomy in 1st 6months of life
familial case seen in adults; 40-50s
In which cases of MTC would you see a solitary nodule and a bilateral/multi-centric nodule?
solitary = sporadic case bilateral = familial case
Which DTC is associated with amyloid deposition?
MTC since amyloid represents deposition of an abnormally folded protein and in MTC case the protein is calcitonin
In which DTC would there be apple green birefringence / stain congo red?
MTC
Name some common paraneoplastic syndromes due to MTC.
Cushing’s - ACTH production
Diarrhoea - VIP production
What is the prognosis of MTC and which drugs are used to treat it?
rapid progression so moderate prognosis
tyrosine kinase inhibitors used (-inib)
What is the undifferentiated form of thyroid carcinoma? Who gets it and what is the prognosis?
anaplastic carcinoma
usually older patients - may have Hx of DTC
aggressive tumours - rapid growth & involvement of neck structures - normally fatal soon after diagnosis (if cut out -> grows back)
What is the first line investigation of a neck lump /suspected thyroid cancer?
USS guided Fine Needle Aspiration (FNA) of the lesion
= thyroid cytology
Why are FNA interpreted without architecture? And in which DTC does this cause an issue?
provides minimally invasive assessment of the likelihood of malignancy
Follicular lesions can be difficult to interpret as relationship to capsule not assessed
What is the grading system for FNA?
Thy1 = uninterpretable Thy2 = benign Thy3 = atypic probably benign/some questionable features Thy4 = atypic suspicious of malignancy Thy5 = malignant
Which FNA result would make you repeat the test?
Thy3
Which FNA result would make you send the patient straight to surgery for removal?
Thy4 or 5
At which grade are follicular lesions automatically graded?
Thy3
What other investigations might you do/not do regarding a thyroid neoplasm?
can do excision biopsy of lymph node
no role for isotope thyroid scan or CT/MRI
pre-op laryngoscopy if suspected vocal card palsy
List some clinical predicators of malignancy.
new thyroid nodule <20 or >50 male nodule increase in size lesion >4cm diameter Hx of head & neck irradiation vocal cord palsy
What are the 2 surgical options for thyroid cancers?
Thyroid lobectomy with isthmusectomy
Sub-total thyroidectomy (+ total thyroidectomy)
Removal of unilateral thyroid nodule; involves exposure of tracheosophageal grooves = ?
thyroid lobectomy + isthmusectomy
Surgical option for papillary micro carcinoma (<1cm diameter) or a minimally invasive follicular carcinoma with capsular invasion only?
thyroid lobectomy
+ patients with a low AMES risk
What risk stratification score is used post-op and what does it include?
AMES Age Metastases Extent of primary tumour Size of primary tumour
<50 y/o female patient /<40 y/o male patient with no evidence of metastasis - AMES group?
low risk AMES
older patient with intra-thyroidal papillary lesion; primary tumour is <5cm & no distant metastases - AMES group?
low risk AMES
older patient with minimally invasive follicular lesion; primary tumour <5cm & no distant metastases - AMES group?
low risk AMES
What is the 20-year survival predicted for a low risk and high risk AMES patient?
low risk = 99%
high risk = 61%
A patient with distant metastases - AMES group?
high risk AMES
Patient with extra-thyroidal disease & papillary cancer - AMES group?
high risk AMES
Patient with follicular carcinoma showing significant capsular invasion - AMES group?
high risk AMES
Older patient with primary tumour >5cm - AMES group?
hight risk AMES
What are the indications for a sub-total/total thyroidectomy?
DTC with extra-thyroidal spread
bilateral/multi-focal DTC
DTC with distant metastasis ± nodal involvement
Patient in AMES high risk group
What is the controversial treatment associated with a patient with DTC + nodal involvement?
lymph node surgery (clearance) controversial since long-term survival unclear
A patient with macroscopic lymphadenopathy -> ?
nodal clearance
Patient with papillary lymph node metastasis -> ?
central compartment clearance AND lateral lymph node SAMPLING
Patient with follicular lymph node metastases -> ?
central lymph node clearance
What is checked within 24hrs of thyroid surgery?
calcium levels
replacement initiated if <2mmol/l
IV calcium for levels <1.8 or if symptomatic
What are some symptoms of hypocalcaemia?
muscle tetany, pins & needles
extreme case - difficulty breathing due to unrelieved contraction of respiratory muscles
What is Chovstecks sign?
tapping over facial nerve -> facial muscle spasm
sign of hypocalcaemia
What is Trousseau sign?
carpo-pedal spasm; inflate BP cuff on arm to 20 mmHg above systolic BP -> carpal spasm due to ulnar nerve ischaemia
What might you see on ECG in hypocalcaemia?
prolonged QT
After which surgery would a patient get a whole-body iodine scan? And how long after the surgery is it?
total or sub-total thyroidectomy
3-6 months post-op
When doing a whole-body iodine scan, which of the patients drugs need to be stopped and how long before the scan?
T4 stopped 4 weeks before scan
T3 stopped 2 weeks before scan
What is rhTSH and when is it given?
recombinant human TSH - given when T3/4 has to be stopped for tests (e.g. whole-body iodine scan) so that patient won’t have episodes of symptomatic hypothyroid
What level should TSH be pre whole-body scan for optimum results?
> 20
What is the typical week-long schedule for a whole-body iodine scan?
Mon/Tues = rhTSH injection
Wed = 2-4 mCi I-131 capsule given
Fri = patient returns for imaging
scan will show any thyroid hormone activity
What is thyroid remnant ablation (TRA)?
Patient is pre-treated with rhTSH
2/3 GBq capsule of i-131 administered
admitted to Lead-lined room
Patient uses disposable cutlery, sheets and clothing is stored until safe; little or no contact with nurses or visitors
Discharged when count rate <500 cps at 1m
What is the follow-up for TRA?
post-therapy scan prior to discharge
Patient is maintained on T4 - aim to suppress TSH <0.1 mU/l and fT4 < 25
thyroglobulin can be used as a “tumour marker”
Why can Tg (thyroglobulin) be used as a “tumour marker” post-TRA?
raised TSH is associated with elevation of Tg levels
anti-thyroglobulin antibodies should be measured at same time as they can affect the interpretation of results
What is the long-term effect of TRA?
small but significant increase in incidence fo AML (acute myeloid leukaemia) in patients with cumulative i-131 disease >800mCi and repeated doses within 12 months
How is recurrent thyroid cancer detected?
clinically by rise in Tg or imaging
Where/how do papillary and follicular DTCs recur?
papillary - in cervical lymph nodes
follicular recurrence is more common - haematogenous spread to lungs, bone or brain
In which group of patients would yo consider a PET scan to check for recurrence?
Those with rising Tg but negative whole-body iodine scan
PET scan in these patients can help identify sites of disease and allow surgery/radiotherapy to be targeted
