Thyroid Nodules Flashcards
What are the indications for performing FNA of a thyroid nodule?
This depends on Hx, US and US doppler results. These nodules should be evaluated for malignancy:
- Solid nodules >10mm size
- Spongy nodules (nodule where more than 50% is made up of microcysts) > 20mm size
- Suspicious ultrasound features:
- hypoechoic
- microcalcificaion
- increased vascularity
- infiltrative margins
- absent halo
- taller than wide - FHx of thyroid cancer
- Hx of head and neck irradiation or exposure to ionising radiation
- Rapid growth of nodule, hoarseness, associated lymphadenopathy
- Hx of thyroid autoimmunity and elevated TSH
What are the possible results of a thyroid nodule FNA according to the Bethesda Classification?
Bethesda Classification: 6 major categories of results that are obtained from FNA
- Non diagnostic
- Benign
- Follicular lesion (lower ratio of colloid to follicles) or atypia of undetermined significance
- Follicular neoplasm
- Suspicious for malignancy
- Malignant
Describe the subsequent management according to the FNA results
- Non diagnostic: repeat US-FNA
- Benign (macrofollicular): follow up and monitor
- Follicular lesion or atypia (repeat FNA after 3 - 6 months or earlier)
- Follicular neoplasm (microfollicular): order TFTs,
- -> if TSH is low then order a thyroid scintigraphy, if non functioning then surgery, if functioning then follow up
- -> TSH normal then surgery - Suspicious for malignancy: surgery
- Malignant: surgery
If FNA detects malignant cytology, what should also be performed preoperatively?
Preoperative neck US to assess the central and lateral neck compartment LNs
If suspicious LN: US guided FNA sent for cytology
Other imaging is not recommended i.e. CT, MRI, PET
What are the surgical mgmt options for thyroid cancer?
a. Total thyroidectomy:
For total:
- Papillary Ca has high predilection for lymphatic spread
- Chance of bilateral disease is high
b. Hemithyroidectomy
Compare the spread of papillar v follicular Ca
Papillary Ca: spread by lymphatics - local LNs
Follicular Ca: spread haematogically: distant mets (bony mets) are common
Adjunctive therapies for thyroid cancer
- Radioactive iodine remnant ablation:
- Recombinant human TSH (Thyrogen)
- Withdraw Thyroxine - Thyroid hormone suppression therapy with thyroxine
How should multinodular goitres be evaluated for malignancy?
Those nodules with suspicious sonographic appearance should undergo FNA preferentially.
If none have suspicious features, the risk of malignancy is low and it is reasonable just to FNA the largest nodules
Indications for surgery in multinodular goitre
- Evidence of malignancy
- Increasing size of dom nodules
- Symptomatic (pressure symptoms, hoarseness)
- Retrosternal extension
Follow-up of patients with multinodular goitre
- Annual clinical Px
- Serial US should be performed
If increasing size of nodules, then they should undergo repeat FNA
If nodules have remained stable for 12-24 months, the interval before the interval between the next clinical Px or US may be longer (e.g. 3-5 years)
Treatment options for autonomous single toxic nodules
- Anti-thyroid drug Rx: carbimazole, propylthiouracil (PTU)
- Surgery
- Radioactive Iodine I131 treatment
List the advantages and disadvantages of anti-thyroid drug Rx for autonomous toxic nodule.
Ad:
- Useful as short term measure
- Rapidly correct thyroid function and alleviate Sx
- Can be used prior to surgery to ensure pt is euthyroid and fit for surgery. Importance: surgery has high risk of thyrotoxic storm that leads to increase release of thyroid hormone and increasing risk of stroke
Dis:
- Will not effect a permenant cure
- AFx: rash (common - 5%), agranulocytosis (rare), abnormal LFTs with PTU only
List ad and disadvatanges of Radioactive Iodine (I131) treatment for autonomous toxic nodule.
Ad:
- High chance of total cure
- One single oral admin
- Essentially non invasive
Dis:
- Possibility of long term hypothyroidism
- Onset of actio ncan be slow: effect usually 4-6 weeks, but can take up to 6 months
- Dosing is imprecise
- C/I in pregnancy
