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Endocrinology > Thyroid Nodules: Clinical, Pathologic > Flashcards

Thyroid Nodules: Clinical, Pathologic Flashcards

1
Q

Thyroid Nodules

A

a. Thyroid nodules are lumps which commonly arise within an otherwise normal thyroid gland.
i. They indicate a thyroid neoplasm, but only a small percentage of these are thyroid cancers.

b. Often these abnormal growths of thyroid tissue are located at the edge of the thyroid gland and can be felt as a lump in the throat.
i. When they are large or when they occur in very thin individuals, they can sometimes be seen as a lump in the front of the neck.

c. Only a small percentage of lumps in the neck are malignant (around 4 – 6.5%[11]), and most thyroid nodules are benign colloid nodules.

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2
Q

Prevalence of Endocrine Disorders in U.S.

A 
Metabolic syndrome	35%
Obesity				20-30%
Diabetes				6-22%
Hypercholesterolemia	17%
Osteoporosis			6-7%

Thyroid nodules—> 30-60%
25 year-old 10%
70 year-old 55%

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3
Q

How are Thyroid Nodules Discovered?

A
  1. Noted by pateient–> 40%
  2. Noted by third party—> 30%
  3. Detected by other test—> 30%
    i. Ultrasound, CT scan, MRI

Retrospective cohort study
299 patients referred to surgical clinic

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4
Q

Thyroid Nodules- The problem

A

a. Thyroid nodules are common (nearly 60%)

b. The risk of cancer in a thyroid nodule is small
i. (10-15% malignant), BUT not insignificant

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5
Q

Normal Thyroid

A

a. See normal follicular cells surrounding the lumen space of the thyroid
i. should be orderly

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6
Q

C cells (calcitonin stain)

A

a. Hard to see

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7
Q

Thyroid Neoplasms

A

a. Benign
Adenoma

NIFTP (rare, non-invasive follicular thyroid neoplasm with papillary nuclear features)

b. Malignant
1. Papillary (85-90%) multifocal, LN

  1. Follicular/Hurthle (5%) vascular spread
  2. Anaplastic (<2%) very aggressive
  3. Medullary (5%) familial

Others malignant
Lymphoma (rare)
Sarcoma (rare)
Metastatic (rare)

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8
Q

Thyroid adenoma

A

a. Benign neoplasm
b. Solitary nodule
c. Follicular / Hurthle cell

d. DDx: hyperplastic nodule
i. follicular ca

  • Critical–>Careful evaluation of the capsule
    i. if there invasive lesion in capsule–> It is Thyroid Carcinoma
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9
Q

Follicular/Hurthle cell Carcinoma

A

Two types of Carcinoma:

  1. Minimally invasive:
    i. Vascular or capsular invasion
  2. Widely invasive:
    More extensive invasion into the surrounding muscle, vessels, trachea ect.
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10
Q

Follicular Carcinoma, Minimally invasive

A

Minimally invasive carcinoma:
i. Vascular or capsular invasion

b. A bunch of micro follicules that are invading potentially into vessel
c. Abornmal lesion or growth

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11
Q

Follicular Carcinoma, Widely invasive

A

Widely invasive:

More extensive invasion into the surrounding muscle, vessels, trachea ect.

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12
Q

Papillary Carcinoma

A

a. Most common
i. papillary due to finger like

b. Well-differentiated
c. Multifocal
d. Lymphatic spread

e. Excellent prognosis
i. even if it invades lymph nodes

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13
Q

Papillary Carcinoma- Histology

A
  1. Papillae with vascular core
  2. Optically clear nuclei
    i. Nucleus is pushed to edge of cell
    ii. Clear center of cell *Critical to know
  3. Nuclear pseudoinclusions
    i. little round inclusions inside the nuclei
  4. Nuclear grooves
  5. Rare or absent mitoses
  6. Psammoma Bodies
    i. little areas of calcifications
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14
Q

Follicular Variant of Papillary Thyroid Cancer

A

a. Variant of the highly common papillary thyroid cancer

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15
Q

Papillary Carcinoma

Summary points

A

a. Most common

b. Well-differentiated
i. Multifocal
ii. Lymphatic spread

c. Excellent prognosis

d. Histology:
Papillae with vascular core
*Optically clear nuclei
*Nuclear pseudoinclusions
Nuclear grooves
Rare or absent mitoses
*Psammoma Bodies-->Ca2+ deposits
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16
Q

Thyroid Gland - Anaplastic Carcinoma

A

a. Older age group (poor survival)
b. Rapidly growing mass

c. Three patterns:
1) Spindle cell
2) Giant cells
3) Squamoid cells

d. Necrosis and hemorrhage
i. more common in anaplastic, not seen in thyroid carcinoma

17
Q

Transition to Anaplastic

A

a. Will see transition from carcinoma to aplastic
i. see more ugly and undifferentiated cells

b. Will see Necrosis and hemorrhage

18
Q

Anaplastic Thyroid Carcinoma

A

a. Metastasis can be anywhere (lungs, liver, ect)

19
Q

Thyroid Gland - Medullary Carcinoma

A

a. Solid proliferation of cells with granular cytoplasm (C cells)
b. Highly vascular stroma

c. Hyalinized collagen and/or amyloid
i. will see these deposited*

d. May have Psammoma bodies (Ca2+ deposits)

Immunostains:
Thyroglobulin -, Calcitonin +, Chromogranin +

20
Q

Thyroid Gland - Lymphomas

A

a. Often arise in long-standing autoimmune thyroiditis
b. Large fleshy masses
c. DDx : anaplastic carcinoma of thyroid
d. Positive LCA, usually B-cell Lymphoma
e. Gene rearrangement can prove clonality
f. Immunophenotyping can be performed on FNA

21
Q

Thyroid Gland - Other Tumors

A

a. Sarcomas: (RARE)

b. Metastatic Tumors: (RARE)
Melanoma Renal
Lung Breast
Head & neck Colon

22
Q

Clinical Evaluation

A

a. HistoryL
Growth
Pain
Cough, voice change

b. Irradiation
i. radiation will increase in risk, find out in history

c. Family history—> possible genetics

d. Physical examination:
Size
Consistency
Fixation
Lymphadenopathy
23
Q

Clinical Evaluation

High clinical suspicion

A

a. High clinical suspicion:
- Rapid tumor growth
- Very firm nodule (rock hard)
- Fixation to adjacent structures
- Vocal cord paresis
- Enlarged regional lymph nodes

b. Genetic suspicion:
i. Family history of PTC or MEN 2

c. Distant metastases

d. Predictive value
i. Positive Predictive Value (PPV) – good (70-75%)
- these signs/symptoms are VERY predictive of possible neoplasm

ii. Negative Predictive Value (NPV) – unacceptable (85%)

24
Q

Approach to the Patient with Thyroid Nodules

A

Things to Do:

  1. Measure Serum TSH
    i. low TSH means there unlikely to be cancer
  2. Diagnostic Ultrasound of neck
  3. Fine Needle Biposy
    i. can help us determine if malignant, benign, non-diagnostic, intermediate
25
Q

Thyroid Nodules- Streamlined work-up

A

TSH
Ultrasound
Fine-needle aspiration biopsy

26
Q

Thyroid Nodule Biopsy

A

a. One approach used to determine whether the nodule is malignant is the fine needle biopsy (FNB), which some have described as the most cost-effective, sensitive and accurate test.
b. FNB or ultrasound-guided FNA usually yields sufficient thyroid cells to assess the risk of malignancy, although in some cases, the suspected nodule may need to be removed surgically for pathological examination.
c. The report may be done according to the Bethesda System for Reporting Thyroid Cytopathology.

27
Q

Fine-Needle Aspiration Biopsy/Accuracy

A

a. Very accurate at finding malignant (98%)
i. good for finding malignant

b. Will find benign and suspicious DX at a lower rate
c. We have a scan for suspicious tumors that we cannot determine if malignant or benign

28
Q

Papillary Carcinoma of Thyroid - Cytologic Features

A
  1. Highly cellular aspirate
  2. +/- colloid
  3. Nuclear enlargement, elongation
  4. Nuclear grooves, pseudoinclusions
  5. Multiple small to large nucleoli
  6. Psammoma bodies
  7. Papillary cellular aggregates
29
Q

Bethesda System

A

a. The Bethesda system (TBS) is a system for reporting cervical or vaginal cytologic diagnoses, used for reporting Pap smear results
b. Can be used for thyroid pathology, will be able to use this report to share info with pathology
c. There are six categories: Non-Diagnostic, Benign, ACUS, suspicition for follow up neoplasm, Suspicious for Malignant, and Malignant

30
Q

Genetics of cancer

A

a. Proto-oncogene—> Normal gene which codes for a protein that promotes normal cell division
b. Oncogene—> Mutated gene which codes for a protein that causes unregulated cell division
c. Tumor Suppressor Gene–> Normal gene which codes for a protein that restrains cell division or that promotes cell differentiation, DNA repair or apoptosis

31
Q

Basic Concepts

A

a, Tumors result from oncogene activation or tumor suppressor gene loss

b. Cells transformed by genetic mutations are likely to develop more mutations
c. Cancers result from multiple sequential genetic mutations

32
Q

Malignant thyroid neoplasms to know

A
  1. Papillary (85-90%) multifocal, LN
  2. Follicular/Hurthle (5%) vascular spread
  3. Anaplastic (<2%) very aggressive
  4. Medullary (5%) familial

Others malignant
Lymphoma (rare)
Sarcoma (rare)
Metastatic (rare)

33
Q

Solid proliferation of cells with granular cytoplasm (C cells)

i. Highly vascular stroma
ii. Hyalinized collagen and/or amyloid

A

Thyroid Gland - Medullary Carcinoma

a. Solid proliferation of cells with granular cytoplasm (C cells)
b. Highly vascular stroma

c. Hyalinized collagen and/or amyloid
i. will see these deposited*

d. May have Psammoma bodies (Ca2+ deposits)

Immunostains:
Thyroglobulin -, Calcitonin +, Chromogranin +

34
Q

Molecular Mechanisms (Papillary Ca)

A

RET/PTC
Rearrangement
20%

a. Mutations associated with papillary thyroid cancer are mainly two forms of chromosomal translocation and one form of point mutation.
i. These alterations lead to activation of a common carcinogenic pathway—the MAPK/ERK pathway.

b. Chromosomal translocations involving the RET proto-oncogene (encoding a tyrosine kinase receptor that plays essential roles in the development of neuroendocrine cells) occur in approximately a fifth of papillary thyroid cancers.
c. The fusion oncoproteins generated are termed RET/PTC proteins (ret/papillary thyroid carcinoma), and constitutively activate RET and the downstream MAPK/ERK pathway.
d. The frequency of ret/PTC translocations is significantly higher in papillary cancers arising in children and after radiation exposure.[1] The gene NTRK1 (encoding the TrkA receptor

e. Approximately a third to a half of papillary thyroid carcinomas harbor point mutations in the BRAF oncogene, also activating the MAPK/ERK pathway.
i. In those cases the BRAF mutations found were V600E mutation

35
Q

p53 in thyroid cancer

A

a. Oncogene gain of function is the most frequent molecular alteration described in thyroid cancer.
i. It mainly includes the aberrant activation of the RAS/RAF/MEK/ERK pathway\
ii. These alterations regard the rearrangements of Ret/PTC and Trk tyrosine kinase receptors and point mutations of RAS or BRAF genes

b. Loss of function of tumor suppressor proteins may also occur in thyroid cancer and includes PAX-8/PPARγ rearrangement, PTEN down-regulation, β-catenin, and p53 mutations
c. While inactivating mutations of the p53 gene is very frequent in human cancers (50% of all human malignancies), they have been found in only 10% of thyroid carcinomasand mainly in poorly differentiated and aggressive histotypes.

d. These observations and the indolent progression of most thyroid carcinomas have brought to the paradigm that p53 role is minor in thyroid cancer initiation and early stages, while it is important only in the rare case of progression to aggressive phenotypes
i. However, the role of p53 functional inactivation in thyroid cancer has never been carefully studied and remains controversial.

36
Q

Poorly differentiated thyroid cancers

A
  • P53 mutation can lead to anaplastic carcinoma
    i. know this

While inactivating mutations of the p53 gene is very frequent in human cancers (50% of all human malignancies), they have been found in only 10% of thyroid carcinomasand mainly in poorly differentiated and aggressive histotypes.

Endocrinology (31 decks)

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