Thyroid Cancer Flashcards
(35 cards)
more clinically aggressive
PDTC and ATC are also thought to arise from follicular cells but are more clinically aggressive compared to DTC due to their loss of differentiation.
MTC, unlike the other tumors described, arise from the neuroendocrine parafollicular C cells.
MC
PTC and FTC representing 84% and 11%, respectively, of all thyroid cancer diagnoses.
MTC represents 2%, and
ATC occurs in 1% of all cases.
PTC
- disseminates primarily via the lymphatic route
- affects the cervical lymph nodes in the central and lateral compartments
- Histologically :
complex branching papillae with pseudoinclusions, nuclear grooving, and psammoma bodies
follicular variant of PTC (fvPTC)
has a similar prognosis to classical PTC and histologically has well-defined follicles with minimal papillary projections.
Other less common but more aggressive histologic subtypes of PTC include
tall cell
hobnail
diffuse sclerosing
and columnar variants
which together comprise less than 1% of all PTCs.
FTC
- spread is hematogenous, typically to the lungs and bone
- FTC cannot be reliably diagnosed by FNA.
- only be definitively diagnosed on histologic examination based on the presence of capsular and vascular invasion
HCC / Oncocytic
- less common type
- more aggressive behavior
- older adults
- Metastases can occur both via lymphatic and hematogenous
- less RAI-avid compared to other DTCs
- 38% of primary tumors being RAI avid
- RAI treatment is associated with improved survival in patients with HCCs that are 2 to 4 cm.
- HCC is distinguished from FTC histologically by the presence of oxyphilic Hürthle (or oncocytic) cells;
> > cellular enlargement with abundant eosinophilic granular cytoplasm due to an increased number of mitochondria
two main subtypes of fvPTC were described: encapsulated and invasive (unencapsulated)
- encapsulated fvPTC »_space; “noninvasive follicular thyroid neoplasm with papillary-like nuclear features,” or NIFTP
- NIFTPs are far more indolent and less concerning than their invasive counterpart
two major molecular mechanisms governing thyroid follicular cell oncogenesis are
the mitogen-activated protein kinase (MAPK) signaling
and
the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathways
MAPK signaling pathway
BRAF, RET/PTC, RAS, and neurotrophic tropomyosin receptor kinase (NTRK)—have been directly linked to the development of DTC.
PI3K/AKT pathway
mutations in PTEN
» an inhibitor of AKT activation
are found in both sporadic FTC and FTC associated with Cowden syndrome,
> > a hereditary disorder characterized by
- multiple hamartomas, particularly of the skin and mucous membranes
- macrocephaly
- increased risk of other solid organ cancers such as breast cancer, endometrial cancer, and colorectal cancer.
RF for Thyroid Cancer
history of ionizing radiation exposure and
family history of DTC.
ionizing radiation exposure in childhood and adolescence in particular is clear for
PTC and perhaps ATC
Family Hx ?
Gardner syndrome (which predisposes to PTC)
Cowden syndrome (FTC and occasionally PTC)
Carney complex (PTC and FTC)
Werner syndrome (PTC and FTC)
familial non-MTC»_space; families with two or more first-degree relatives diagnosed with DTC in the absence of other hereditary cancer syndromes.
Thyroid Cancer usually Painless, if Painful Suspect What ?
pain can also be indicative of less common and more aggressive thyroid cancers such as
MTC, primary thyroid lymphoma, and ATC.
When to do CT, MRI, Laryngoscopy ??
(contrast-enhanced CT or MRI of the neck and chest)
and intraluminal imaging (laryngoscopy, bronchoscopy, or esophagoscopy)
> > in patients with potentially more advanced local and regional disease.
voice changes, dysphagia, respiratory symptoms such as cough or hemoptysis, as well as palpable evidence of rapidly enlarging, bulky, and/or fixed disease on physical exam
ipsilateral thyroid lobectomy in DTC
> > for low-risk unilateral DTCs
between 1 and 4 cm
without extrathyroidal extension or evidence of metastatic disease
> > and it is the recommended surgical option for DTCs that are less than1 cm
total thyroidectomy is now the preferred evidence-based approach only for
> > at higher risk for recurrence and/or disease-specific mortality
- Tumor at least 4 cm
- Gross extrathyroidal extension
- Evidence of metastatic disease
- Radiation-induced DTC
- Familial nonmedullary thyroid cancer
- Multifocal bilateral DTC.
clinical and/or radiographic evidence of cervical lymph node metastases
> > therapeutic compartment-based lymph node dissection is recommended
most relevant nodal stations for thyroid cancer include
> > the central compartment (level VI and VII)
which consists of the perithyroidal lymphoadipose tissue bounded by the carotid arteries laterally, the hyoid bone superiorly, and the innominate artery inferiorly
> > the lateral compartments containing the jugular groups (levels II, III, and IV) and the inferior posterior triangle (level Vb).
Therapeutic lymph node dissection should be performed in patients with
> > radiographic or clinical evidence of metastatic disease as determined either preoperatively or intraoperatively
The presence of ipsilateral central compartment nodal involvement warrants a
level VI (+/-VII) dissection
The presence of lateral neck nodal metastases warrants
> > both a central and lateral compartment-based neck dissection, even in the 12% of patients with skip metastases to the lateral neck (i.e., bypassing the central neck nodes).
the ATA guidelines suggest that prophylactic central neck dissection should be considered for certain higher risk patients with
> > cN0 papillary thyroid carcinomas with more advanced primary tumors (T3 or T4)
> > clinically involved lateral neck nodes
> > if the information would be helpful in guiding additional therapy.
Active Nonoperative Surveillance of PTC
nonoperative active surveillance for papillary thyroid microcarcinomas smaller than 1 cm
> > Some Studies
