Thyroid cancer Flashcards
What are the essential elements of history-taking in patient with thyroid pathologies?
1) RIsk factors : radiation (environmental or previous radiotherapy), familial hx (gardner, PTEN syndrom eg cowden - hamartomatous polyposis, MEN 2 A-B, familial medullary cancer)
2) aerodigestive symptoms
3) hypo/hyperthryroidism sx
what is the baseline investigation used for thyroid nodules?
US thyroid + neck
CXR
TSH
no need for thryoid I123 scan except if has low tsh and suspecting warm nodule (instead of a diffuse goiter)
What are the signs on US which would orient towards a malignant nodule?
Hypoechogenic
microcalcifications
ill defined edges
Suspicious LN:
looses fatty hilum, looses kidney shape and becomes rounder, microcal.
What is the rationale of an FNA?
it is often non diagnostic but will change management (from a hemi to a total) if a papillary / hurtle cell / medulary carcinoma is found.
Can you diagnose follicular cancer via FNA?
no. Capsular invasion needs to be documented as a marker of malignancy.
What is are Hurtle cell. What does Hurtle cells metaplasia means from a histological standpoint?
Hurtle cells are follicular in origine, but as they accumulate mitochondria as a result of adaptative changes (metaplasia). they are oncocytic (cytoplasm contains numerous mitochondria) and oxyphilic (afinity for acid stains)
Metaplasia is most often seen in benign processes such as thyroiditis, goiter, hyperplastic nodules.
in a specimen, What % of hurtle cells is required for the diagnosis of hurtle cell adenoma/carcinoma
> 75%
If below threshold, the term follicular neoplasm with hurtle cell metaplasia will be used.
prognosis of hurtle cell carcinoma is similar to follicular carcinoma. worsens if evidence of vascular invasion.
What is the malignancy rate in pediatric nodules?
25 %
female predominance with 4:1 ratio.
5 % in adults…
Risk factor for malignant nodules?
< 10 yo Male Hx radiation Has a familial syndrome (Gardner, cowden) Aerodigestive sx lesion > 4 cm Evidence of adenopathy
What is the histological classification of carcinomas?
Differentiated
-papillar or follicular
Undifferentiaded
-anaplastic, medullary
All can be diagnosed by FNA except follicular for which architecture (capsular invasion) needs to be assessed.
What is the management if a follicular lesion is identified on FNA?
needs surgical biopsy (hemithyroidectomy)
What are the Bethesda categories?
1. inadequate specimen benign 3. follicular lesion of undertermined significance 4. follicular neoplasm 5. suspected malignancy 6. malignancy
What is the management based on bethesda?
Lobectomy is the surgical management for lesions other than malignant .
If comes back follicular carcinoma, may need completion.
- inadequate specimen: repeat FNA
- Benign: f/u imagina PE
- Follicular of indeterminate significance: lobectomy
- follicular neoplasm : lobectomy
- Suspected malignant: lobectomy
- Malignant (all but follicular histology): total consider central neck dissection
When to perform a lymphnode dissection?
Management is controversial. Dissection is for papillary cancer. If evidence of intraop Or proven preop (FNA) disease, perform a central dissection (hyoid to sternal notch, with carotid sheaths as lateral landmarks).
Concerning prophylactic dissection: depends on comfort level and characteristics of tumor (very large, agressive…)
central dissection associated with hypocalcemia (para)
What are the characteristics of papillary vs follicular carcinoma?
Papillary (90% of differentiated). Often multifocal, and bilateral. Metastasis predominently via lymphatics.
Follicular: 10% of differentiated. hematogenous spread to lungs and bones.
What are classic histological findings of papillary tumors?
Orpan annie eye
nuclear grooving.
a follicular carcinoma is identified in a hemithyroidectomy specimen. under which circumstances should you perform a thyroidectomy completion?
complete thyroidectomy if any of:
> 4 cm
Lymphovasc invasion
Known mets
What specific workup should be ordered if medullary carcinoma is suspected?
calcitonin
What is the appropriate surgical timing for patient with RET mutations?
high risk group (MEN2B) codon M918T: < 1st year of life
The 2 other groups includes MEN2A and familial medullary
- intermediate : surgery < 5 yo
- Low: start screening at 5 yo
Central dissection if clinical involvement. preserve parathyroid.
What is the role of I123 scan postoperatively?
in intermediate to high risk patient with differentiated carcinoma, an Nuclear scan using I 123 is obtained. Patient needs to have a high TSH level so appropriate timing with no syntroid supplementation is required.
If scan lights up, then patient is given I 131.
a repeat nuclear scan is done afterwards .
How are patients followed postop.
US / tumor marker (thyroglobulin or calcitonin) Q 6 months, then space out.
What is an ectpic thymic rest?
intra thyroidal lesion, hypoechoic with microcal and linear internal echo. Very lymphocytic on biopsy.
conservative management with serial US.
Name 3 benign lesion which can be intrathyroidal?
thymic rest
thyroglossal cyst
branchial cyst (3-4), almost always on the L lobe.
