Thyroid Cancer Flashcards
(26 cards)
If you do an ultrasound of thyroid nodules and find that 1 nodule is suspicious but the other is normal looking, on which one should you perform an FNA?
Both due to risk of mets
If you have an inadequate sample for FNA on a thyroid nodule, when is the soonest you can repeat the FNA?
have to wait at least 3 mos
What is the most common endocrinopathy associated with immune checkpoint inhibitors? (Example = Nivolumab)
primary hypothyroidism
the big circles are psammoma bodies, which are calcifications seen in PTC
What calcitonin level is concerning for metastatic MTC?
> 150
What imaging should be obtained if you are worried about metastatic medullary thyroid carcinoma?
CT neck and chest
How does medullary thyroid cancer spread?
mostly via lymphatics but sometimes hematogenously (think L in meduLLary for Lymphatics)
When should you do a prophylactic thyroidectomy due to medullary thyroid cancer?
- Must be due to MEN2A/B (remember, this is a mutation in the RET proto-oncogene).
- Mutation in codon 918 = remove < 1yo
- Mutation in codon 234 = remove < 5yo
How do you tx confirmed medullary thyroid carcinoma?
- Surgery (total thyroidectomy + LN dissection)
- No RAI
- Maintain normal TSH
- Monitor calcitonin and CEA
What are the tumor markers for PTC, FTC, and MTC?
- PTC = TG and anti-TG
- FTC = TG and anti-TG
- MTC = calcitonin and carcinoembryonic antigen (CEA) as these are secreted by parafollicular C-cells
What are the 2 kinds of MTC and how can you tell them apart?
- Germline: AD mutations in RET proto-oncogene, which causes MEN2A/B. Accounts for most of MTC. Is multifocal on imaging w/ C-cell hyperplasia.
- Somatic: Sporadic fusion mutations of RET, RAS, and ALK. Is unifocal w/out C-cell hyperplasia.
After surgery for differentiated thyroid cancer, how do you determine who is at higher risk for residual/recurrent disease? Based on their level of risk, how do you treat?
- Low risk: Mainly in the gland –> just get a TG level and keep TSH 0.5-1.0
- Intermediate risk: Some neck involvement –> TSH-stimulated TG level and diagnostic I-123 scan –> ablate w/ I-131 if persistent disease and keep TSH 0.1-0.5
- High risk: Extensive neck involvement w/ or w/out mets –> TSH-stimulated TG level and diagnostic I-123 –> ablate w/ I-131 if persistent disease and keep TSH <0.1
What are the molecular causes of PTC?
Usually due to fusion mutations of the following in this order:
1. RET
2. BRAF
3. NTRK
4. RAS
5. PTEN
What are the differences between papillary vs follicular thyroid cancer?
- PTC: mets to local lymph nodes w/ significant neck involvement, hematogenous mets to lungs, bilateral
- FTC: no lymph nodes, hematogenous mets to lungs or bone, unilateral
Where do most common thyroid cancers originate from in the thyroid?
- PTC and FTC come from follicular cells
- MTC comes from parafollicular C-cells
What Bethesda scores for thyroid nodules are guarantees for thyroid surgery?
4-6
What is the Bethesda system?
Approach to interpreting FNA cytology from a thyroid nodule and determining next steps
1 = non-diagnostic –> repeat FNA
2 = benign –> repeat u/s in 6-12 mos. If nodule > 4 cm at repeat u/s, go ahead and take out.
3 = atypia or undetermined significance (think ASCUS) –> repeat FNA or lobectomy and send molecular testing
4 = follicular neoplasm –> lobectomy
5 = suspicious for malignancy –> lobectomy or total thyroidectomy
6 = malignant –> total thyroidectomy
ectopic thymus = benign/nothing to do
What are the features of benign thyroid nodules?
CSS
- Cystic
- Spongiform (lots of tiny cysts)
- Smooth borders
macrocephaly + thyroid cancer =
Either PTEN hamartoma tumor syndrome (AKA Cowden) or DICER1 syndrome
What are the 3 main types of malignant thyroid nodules and which one is most common?
papillary > follicular > medullary
What are the suspicious findings of a thyroid nodule?
SHIT CA
- Solid
- Hypoechoic (black)
- Irregular margins
- Taller than wide
- Calcifications
- Abnormal lymph nodes
How do you work up a thyroid nodule?
What is PTEN hamartoma syndrome?
- AKA Cowden syndrome
- AD mutation in PTEN, which is a tumor suppressor gene
- Phenotype: Female HAM = female cancers (ovarian, breast, uterine), hamartomas, autism, macrocephaly
