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Endocrine > 174. Thyroid Histology/Pathology > Flashcards

174. Thyroid Histology/Pathology Flashcards

1
Q

Gross:

  • varies considerably depending on the presence and degree of fibrosis, encapsulation, and cystic change
  • often a multifocal process
  • microcarcinoma is < 1.0 cm

Surgery:
- near total thyroidectomy

A

Papillary carcinoma (PTC)

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2
Q

Integrity of the ___ is important in determining malignant potential of follicular adenoma

A

tumor capsule

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3
Q

From cytology (FNA):

  • repetitive pattern of microfollicles and rosettes
  • single cell type, scant colloid
A

Follicular/Hurthle Cell Neoplasm

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4
Q

As the thyroid descends anterior to the pharyngeal gut it is connected to the tongue by the __ which normally obliterates in week 7-10

A

Thyroglossal duct

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5
Q

Histology:

  • high-grade carcinomas with no obvious follicular differentiation by histology or immunohistochemistry
  • variety of morphologic patterns
  • extreme cellular/nuclear pleomorphism, necrosis

Management:
- mainly palliative

A

Anaplastic Carcinoma

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6
Q

Gross:
- typically discrete, solitary, non-functional masses derived from follicular epithelium

Clinically difficult to distinguish from dominant nodules in a hyperplastic gland and it is usually impossible to predict which ones are follicular carcinomas until they are excised

Comprise about 5-10% of thyroid nodules

A

Follicular/Hurthle Cell Adenoma

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7
Q

Gross:
- Diffusely enlarged gland, solitary nodule presentation seen in more cases

Histology:

  • Extensive infiltration of parenchyma by small lymphocytes/plasma cells with germinal centers
  • Follicles atrophic, lined by regenerating Hurthle cells
  • –> metaplastic response to the normally low cuboidal epithelium to ongoing injury

Cytology (FNA):
- Hurthle cells + a heterogeneous population of lymphoid cells

A

Hashimoto’s thyroiditis (Chronic lymphocytic thyroiditis)

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8
Q

Gross:

  • Non-encapsulated, bu border can sometimes be circumscribed
  • Arise from the junction of the middle and upper thirds of the thyroid lobes

Sporadic - solitary nodule

Familial - bilateral and multicentricity

Surgery:
- total thyroidectomy with lymph node dissection

A

Medullary Carcinoma (MTC)

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9
Q

Rare

Common sites: Kidney, lung, breast

Whenever pattern is “alien” think about this and anaplastic carcinoma

Very poorly differentiated tumors may be virtually impossible to distinguish morphologically from anaplastic carcinoma

A

Metastatic tumors

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10
Q

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features

Encapsulated follicular variant of PFT

Clinically and genetically behaves more like a follicular neoplasm

A

NIFTP

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11
Q

Autoimmune destruction of the gland caused by circulating Abs against thyroglobulin and thyroid peroxidase (TPO)

Most common in 45-65 year olds
- female

Increased risk for developing:

  • other autoimmune diseases
  • B-cell non-Hodgkin lymphomas (MALT lymphomas)
  • Papillary thyroid carcinoma
A

Hashimoto’s thyroiditis

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12
Q

Spectrum of changes:

  1. Hyperplastic stage: follicle lumen small, scant colloid, tall columnar epithelium, some papillae
  2. Degenerative changes: fibrosis, hemorrhage, regeneration/repair, dystrophic calcification
  3. Involutional stage: follicles distended w/ colloid, lined by small cuboidal/flat epithelium
A

Adenomatous (colloid or hyperplastic) nodules

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13
Q

Histology:

  • variable: composed of polygonal to spindle-shaped cells, which form nests, trabeculae, and follicles
  • Acellular amyloid deposits derived from altered calcitonin polypeptides are seen in adjacent stroma
  • calcitonin stain positive in tumor cell and the stromal amyloid
  • familial has multicentric C-cell hyperplasia
A

Medullary Carcinoma (MTC)

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14
Q

An enlarged intrathyroidal parathyroid

Clear fluid drawn on FNA
- difficult to distinguish from follicular cells

Can do immunostains for TTF/PTH or send FNA for biochemical PTH assay

Use sestamibi scan to highlight

A

Parathyroid cyst/adenoma

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15
Q

Multiple cycles of hyperplasia and involution lead to..

A

Nodularity

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16
Q

Most common cause of endogenous hyperthyroidism

Caused by breakdown in self-tolerance to thyroid autoantigens, most importantly TSH receptor

Peaks b/w 20-40 years old

Classic triad:

  • hyperplasia of gland
  • ophthalmopathy
  • dermatopathy

Treated w/ thioamides or I-131

A

Graves’ Disease

17
Q

Descent/maturation to adult shape for the thyroid completed in week __ of gestation

A

Week 7

18
Q

Technique for acquiring diagnostic material in which a small, thin needle is used to remove cells from a lesion or mass in the body

First line test for investigation of most thyroid nodules

Advantages:

  • simple
  • safe
  • accurate
  • inexpensive
A

Fine Needle Aspiration (FNA) biopsy

19
Q

Inner true capsule, which forms numerous septae, that divide the gland into lobes and lobules

Lobules are composed of 20-40 follicles, the structural units of the gland, which consist of a layer of simple epithelium enclosing a colloid-filled cavity

A

Histology of thyroid

20
Q

Histology:
Lined by cuboidal or squamous epithelium

Contains proteinaceous fluid

Follicles may or may not be present

A

Thyroglossal duct cyst

21
Q

Gross:
- Thyroid is diffusely and symmetrically enlarged

Histology:

  • Papillary hyperplasia with tall follicular cells (secreting colloid) is a common finding
  • –> can cause confusion with PTC
  • benign diffusely seen papillae are broad based, short stubby, and lack nuclear features of papillary carcinoma
A

Graves’ Disease

22
Q

Thyroid cancers without an obvious follicular or papillary pattern
- implies lack of differentiation

Correlate with nests (insulae) on histology

May find follicular or papillary areas on the same slide

A

Poorly Differentiated Carcinomas

23
Q

Histology:

  • characteristically exhibit uniformly sized follicles
  • surround fibrous capsule
  • compression of adjacent follicles

Capsule is usually thin, uniform, and completely intact

Surgically remove lobe

A

Follicular/Hurthle Cell Adenoma

24
Q

When should a thyroid nodule be biopsied?

A

When the size of the nodule is large and US results reveal something concerning

25
Q

Epithelial cells with abundant granular cytoplasm that is rich with mitochondria

A

Hurthle cells

26
Q

Functional unit of the thyroid

A

Follicle containing colloid

27
Q

Hallmark diagnostic feature is atypical nuclear morphology

Hypochromasia 
Nuclear grooves 
Intranuclear inclusions 
Ovoid nucleus 
Micronucleolus
A

Papillary carcinoma (PTC)

28
Q

Genetic changes found in Follicular/Hurthle Cell carcinoma (2 of them)

A

RAS mutations

PAX8-PPARG fusion gene

29
Q

Thyroid starts developing on what gestational day

A

Day 24

30
Q

Where the thyroglobulin and iodide are stored so that follicular epithelial cells can use them to produce thyroid hormones

A

Colloid

31
Q

Where does the thyroid derive from embryologically?

Endodermal

A

1st pharyngeal arch

32
Q

Neuroendocrine neoplasms derived from C cells
- 5% of thyroid neoplasms

75% arise sporadically

Remainder occur in the setting of MEN2A or MEN2B or FMTC

Serum calcitonin and CEA are important markers

A

Medullary Thyroid Carcinoma (MTC)

33
Q

70-75% of thyroid nodules are..

Vast majority of thyroid nodyles are non-neoplastic (benign)

A

Hyperplastic

34
Q

Approximately 5-10% of all thyroid nodules
- 85% of all thyroid malignancies

Young age (20-40yo)

Associated w/ radiation

Nonfunctional

Can present initially as cervical lymph node metastasis

Great prognosis unless metastasis to lymph nodes

Associated w/ activation of MAP Kinase pathway

  • RET rearrangements
  • activating point mutations in BRAF in 30%
A

Papillary carcinoma (PTC)

35
Q

Most common clinically significant congenital anomaly

Abnormal persistence of the thyroglossal duct
- doesn’t obliterate in weeks 7-10

Midline, spherical cystic mass, closely associated with hyoid bone
- moves with swallowing

A

Thyroglossal duct cyst

36
Q

Malignancy in a follicular neoplasm is determined by: (2 things)

A

Capsular invasion

Vascular invasion

37
Q

Removal of a thyroglossal duct cyst where the mid portion of the hyoid bone is also removed

A

Sistrunk procedure

38
Q

Primary or more common secondary in thyroid

Predominantly Non-Hodgkins, B-cell type

75% associated w/ Hashimoto’s

Low grade (MALT) difficult to distinguish from CLT 
- obtain flow cytometry

High grade mimics anaplastic carcinoma clinically

A

Thyroid lymphoma

39
Q

Rare <5% of thyroid tumors

Most undifferentiated carcinomas present with extensive local extension beyond thyroid

Mimics other tumors, including metastasis

Diagnosis:

  • classical clinical history
  • stains by pathology to exclude metastasis
  • may see a concurrent well differentiated component (but not always)
A

Anaplastic carcinoma (undifferentiated)

Endocrine (26 decks)

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