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EndoRepro 2 Exam 2 > Path - Thyroid > Flashcards

Path - Thyroid Flashcards

1
Q

the thyroid is often diffusely enlarged, although more localized enlargement may be seen in some cases

  • the capsule is intact, and the gland is well demarcated from adjacent structures
  • the cut surface is pale yellow-tan, firm, and somewhat nodular
  • extensive infiltration of the parenchyma by a mononuclear inflammatory infiltrate containing small lymphocytes, plasma cells, and well-developed germinal centers
  • follicles are atrophic and are lined in many areas by epithelial cells distinguished by the presence of abundant eosinophilic, granular cytoplasm termed Hurthle cells
A

Hashimoto thyroiditis

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2
Q

in fin needle aspiration biopsy samples, the presence of Hurthle cells in conjunction with a heterogenous population of lymphocytes is characteristic of what?

A

Hashimoto thyroiditis

  • in “classic” Hashimoto thyroiditis, interstitial connective tissue is increased and may be abundant
  • unlike Reidel thyroiditis, the fibrosis does NOT extend beyond the capsule of the gland
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3
Q

except for possible mild symmetric enlargement, the thyroid appears grossly normal

  • microscopic examination reveals lymphocytic infiltration with large germinal centers within the thyroid parenchyma and patchy disruption and collapse of thyroid follicle
  • unlike Hashimoto’s, fibrosis and Hurthle cell metaplasia are NOT present
A

subacute lymphocytic (painless) thyroiditis

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4
Q

the gland may be unilaterally or bilaterally enlarged and firm, with an intact capsule that may adhere to surrounding structures

  • on cut section, the involved areas are firm and yellow-white and stand out from the more rubbery, normal brown thyroid substance
  • histologic changes are patchy and depend on the stage of the disease
A

granulomatous thyroiditis

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5
Q

what is seen early in the active inflammatory phase of granulomatous thyroiditis?

A

scattered follicles may be disrupted and replaced by neutrophils forming microabscesses

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6
Q

what is seen later in the inflammatory phase of granulomatous thyroiditis?

A

more characteristic features appear in the form of aggregates of lymphocytes, activated macrophages, and plasma cells associated with collapsed and damaged thyroid follicles
- multinucleate giant cells enclose naked pools of fragments of colloid

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7
Q

what is seen in late stages of granulomatous thyroiditis?

A

chronic inflammatory infiltrate and fibrosis may replace the foci of injury

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8
Q

what is the most common cause of hypothyroidism, in regions where dietary iodine levels are sufficient?

A

Hashimoto thyroiditis

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9
Q

autoimmune thyroiditis characterized by progressive destruction of thyroid parenchyma, Hurthle cell change, and mononuclear (lymphoplasmacytic infiltrates, with germinal centers and with/without extensive fibrosis

A

Hashimoto thyroiditis

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10
Q

often occurs after a pregnancy, is typically painless, and is characterized by lymphocytic inflammation in the thyroid

A

subacute lymphocytic thyroiditis (postpartum thyroiditis)

- is also a type of autoimmune thyroiditis

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11
Q

self-limited disease, probably secondary to a viral infection, and is characterized by pain and the presence of a granulomatous inflammation of the thyroid

A

granulomatous (de Quervain) thyroiditis

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12
Q

the thyroid is usually symmetrically enlarged due to diffuse hypertrophy and hyperplasia of thyroid follicular epithelial cells

  • increases in weight over 80gm are common
  • on cut section, the parenchyma has a soft, meaty appearance resembling muscle
  • histologically, the follicular epithelial cells in untreated cases are tall and more crowded than usually -> resulting in formation of small papillae, which project into the follicular lumen and encroach on the colloid, sometimes filling the follicles
A

Graves disease

  • the papillae lack fibrovascular cores
  • colloid within the lumen is pale, with scalloped margins
  • lymphoid infiltrates (mostly T cells) along with scattered B cells and mature plasma cells, are present throughout the interstitium
  • germinal centers are common
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13
Q

what does administration of iodine cause in Graves disease?

A

involution of the epithelium and the accumulation of colloid by blocking thyroglobulin secretion

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14
Q

what does treatment with the antithyroid drug propylthiouracil (PTU) cause?

A

it exaggerates epithelial hypertrophy and hyperplasia by stimulating TSH secretion

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15
Q

what are the changes in extrathyroidal tissue listed?

A
  • lymphoid hyperplasia (especially the thymus is younger patients)
  • heart may be hypertrophied (also ischemic changes)
  • pts with ophthalmopathy, the tissue of the orbit are edematous d/t presence of hydrophillic mucopolysaccharides (also lymphocytic infiltration and fibrosis)
  • orbital muscles are initially edematous but may undergo fibrosis late in the course of the disease
  • thickening of the dermis d/t deposition of glycosaminoglycans and lymphocyte infiltration
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16
Q

what is characterized by the triad of thyrotoxicosis, ophthalmopathy and dermopathy?

A

Graves disease

- most common cause of endogenous hyperthyoidism

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17
Q

autoimmune disorder caused by activation of thyroid epithelial cells by autoantibodies to TSH receptor that mimic TSH action

A

Graves disease

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18
Q

how is the thyroid characterized in Graves disease?

A

diffuse hypertrophy and hyperplasia of follicles and lymphoid infiltrates

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19
Q

what causes ophthalmopathy and dermopathy in Graves disease?

A

glycosaminoglycan deposition and lymphoid infiltrates

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20
Q

what are the levels of TSH and free T3/4 in Graves disease?

A
  • free T3/4 are HIGH

- TSH is LOW

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21
Q

what are the two phases of a diffuse nontoxic goiter?

A
  1. hyperplastic phase

2. colloid involution

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22
Q

thyroid is diffusely and symmetrically enlarged, although the increase is usually modest, and the gland rarely exceeds 100-150gms

  • the follicles are lined by crowded columnar cells, which may pile up and form projections similar to those seen in Graves disease
  • the accumulation is not uniform throughout the gland and some follicles are hugely distended, whereas others remain small
A

the hyperplastic phase of a nontoxic goiter

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23
Q

what happens dietary iodine subsequently increases or if the demand for thyroid hormone decreases during the hyperplastic phase of a nontoxic goiter?

A

the stimulated follicular epithelium involutes to form an enlarged, colloid-rich gland -> COLLOID GOITER

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24
Q

what does a colloid goiter look like?

A

the cut surface is usually brown, somewhat glassy, and translucent
- histologically, the follicular epithelium is flattened and cuboidal, and colloid is abundant during periods of involution

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25
Q

multilobulated, asymmetrically enlarged glands that can reach weights of more than 2k grams
- pattern of enlargement is unpredictable and may involve one lobe far more than the other, producing lateral pressure on midline structures (trachea, esophagus)

A

multinodular goiter

  • on cut section, irregular nodules containing variable amounts of brown, gelatinous colloid are present
  • older lesions have areas of hemorrhage, fibrosis, calcification, and cystic change
26
Q

what is it called when the goiter grows behind the sternum and clavicles?

A

intrathoracic or plunging goiter

  • occasionally, most of it is hidden behind the trachea and esophagus
  • sometimes one nodule may stand out, imparting the clinical appearance of a solitary nodule
27
Q

what is seen on microscopy of a multinodular goiter?

A

colloid-rich follicles lined by flattened, inactive epithelium and areas of follicular hyperplasia, accompanied by degenerative changes related to physical stress

28
Q

how do multinodular goiters differ from follicular neoplasms?

A

they lack a prominent capsule between the hyperplastic nodules and residual compressed thyroid parenchyma

29
Q

what features are important in making the distinction between a thyroid adenoma and multinodular goiter?

A

thyroid adenoma is a solitary, spherical, encapsulated lesion that is demarcated from the surrounding thyroid parenchyma by a well-defined, intact capsule

30
Q

in freshly resected specimens, the tumor bulges from the cut surface and compresses the adjacent thyroid

  • color ranges from gray-white to red-brown, depending the the cellularity and its colloid content
  • areas of hemorrhage, fibrosis, calcification, and cystic change, similar to those encountered in multinodular goiters are common
A

follicular adenoma

31
Q

microscopically, the constituent cells often form uniform appearing follicles that contain colloid

  • follicular growth pattern is usually quite distinct from the adjacent nonneoplastic thyroid
  • the neoplastic cells show little variation in cell size, shape, or nuclear morphology
  • mitotic figures are rare
A

follicular adenoma

32
Q

what is the hallmark of all follicular adenomas?

A

the presence of an intact, well-formed capsule encircling the tumor
- careful evaluation of the integrity of the capsule is therefore critical in distinguishing follicular adenomas from follicular carcinomas

33
Q

what does extensive mitotic activity, necrosis, or high cellularity warrant?

A

close inspection to exclude follicular carcinoma and the follicular variant of papillary carcinoma

34
Q

these tumors may be solitary or multifocal

  • some are well-circumscribed and even encapsulated, others infiltrate the adjacent parenchyma and have ill-defined margins
  • tumors may contain areas of fibrosis and calcification, are often cystic
  • the cut surface sometimes reveals papillary foci that point to the diagnosis
A

papillary carcinomas

  • foci of lymphatic invasion by the tumor are often present, but involvement of blood vessels is relatively uncommon, especially in smaller lesions
  • metastases to adjacent cervical lymph nodes occur in up to 50% of cases
35
Q

papillary carcinomas may contain branching papillae, which are what?

A

a fibrovascular stalk covered by single or multiple layers cuboidal epithelial cells

  • in most neoplasms, the epithelium covering the papillae consist of well-differentiated, uniform, orderly cuboidal cells
  • can also have failrly anaplastic epithelium showing considerable variation in cell and nuclear morphology
  • when present, the papillae differ from those seen in areas of hyperplasia in being more complex and having dense fibrovascular cores
36
Q

what do the nuclei of papillary carcinoma cells contain?

A

finely dispersed chromatic, which imparts an optically clear or empty appearance, giving rise to the designation of ground glass or ORPHAN ANNIE EYE NUCLEI
- invaginations of the cytoplasm may give the appearance of intranuclear inclusions (pseudo-inclusions) or intranuclear grooves

37
Q

these concentrically calcified structures are often present in papillary carcinomas, usually within the cores of papillae
- these structures are almost never found in follicular and medullary carcinomas, and so when present in fine needle aspiration material, they are a strong indication that the lesion is a papillary carcinoma

A

psammoma bodies

38
Q

what is the most common variant of papillary carcinoma?

  • has characteristic features of papillary carcinomas and an almost entirely follicular architecture
  • can be either encapsulated or poorly circumscribed and infiltrative
A

follicular variant of papillary carcinoma

39
Q

which variant has a generally favorable prognosis?

A

encapsulated follicular variant

40
Q

which variants need to be treated more aggressively?

A

poorly circumscribed and infiltrative lesions

41
Q

what are the genetic alterations that differ in the follicular variant of papillary carcinomas?

A
  • lower frequency of RET/PTC rearrangements
  • lower frequency and different spectrum of BRAF mutations
  • significantly higher frequency of RAS mutations
42
Q

this variant has tall columnar cells with intensely eosinophilic cytoplasm lining the papillary structures
- these tumors tend to occur in older individuals and have higher frequencies of vascular invasion, extrathyroidal extension, and cervical and distant metastases than conventional papillary thyroid carcinoma

A

tall-cell variant

43
Q

what are the genetic alterations that differ in the tall-cell variant of papillary carcinomas?

A

BRAF mutations and RET/PTC translocations
- the occurrence of these two together may synergistically enhance MAPK signaling, contributing to the aggressive behavior of this variant

44
Q

this variant occurs in younger individuals, including kids

  • tumor has a prominent papillary growth pattern intermixed with solid areas containing nests of squamous metaplasia
  • there is extensive, diffuse fibrosis throughout the thyroid gland, often associated with a prominent lymphocytic infiltrate, stimulating Hashimoto thyroiditis
  • lymph node metastases are present in almost all cases
  • they lack BRAF mutations, but RET/PTC translocations are found in approx 50%
A

diffuse sclerosing variant carcinomas

45
Q

this variant is defined as an otherwise conventional papillary carcinoma, less than 1cm
- lesions most commonly come to attention as an incidental finding in patients undergoing surgery, and may be precursors of typical papillary carcinomas

A

papillary microcarcinoma

46
Q

single nodules that may be well circumscribed or widely infiltrative

  • sharply demarcated lesions may be exceedingly difficult to distinguish from follicular adenomas by gross exam
  • larger lesions may penetrate the capsule and infiltrate well beyond the thyroid capsule into the adjacent neck
  • they are gray to tan to pink on cut section and may be somewhat translucent d/t presence of large, colloid-filled follicles
  • can have degenerative changes, such as central fibrosis
A

follicular carcinoma

47
Q

microscopically, most of these carcinomas are composed of fairly uniform cells forming small follicles containing colloid

  • occasional tumors are dominated by cells with abundant granular, eosinophilic cytoplasm (Hurthle cells)
  • the nuclei lack the features of typical papillary carcinoma, and do NOT have psammoma bodies
A

follicular carcinomas

48
Q

why is the diagnosis of widely invasive follicular carcinoma obvious?

A

they infiltrate the thyroid parenchyma and extrathyroidal soft tissues
- histologically, these cancers tend to have a greater proportion of solid or trabecular growth pattern less evidence of follicular differentiation, and increased mitotic activity

49
Q

these tumors present as a solitary nodule

  • larger lesions contain areas of necrosis and hemorrhage and may extend through the capsule of the thyroid
  • the tumor tissue is firm, pale gray to tan, and infiltrative
  • there may be foci of hemorrhage and necrosis in larger lesions
A

sporadic medullary thyroid carcinoma

50
Q

microscopically, these tumors are composed of polygonal to spindle-shaped cells, which may form nests, trabeculae, and even follicles

  • small, anaplastic cells are present and may be the predominant cell type
  • acellular AMYLOID DEPOSITS derived from calcitonin polypeptides are present in the stroma in many cases
  • calcitonin is readily demonstrable within the cytoplasm as well as in the stromal amyloid -> STAINING
A

medullary thyroid carcinoma

51
Q

what is one of the characteristic features of familial medullary cancers?

A

the presence of multicentric C-CELL HYPERPLASIA

  • is believed to be a precursor lesion in familial cases
  • presence of multiple prominent clusters of C-cells scattered throughout the parenchyma should raise the specter of an inherited predisposition, even if there is no family history
52
Q

most thyroid neoplasms manifest as what?

A

solitary thyroid nodules

- only 1% of nodules are neoplastic

53
Q

what are the most common benign neoplasms?

A

follicular adenomas

54
Q

what are the most common malignancies?

A

papillary carcinoma

55
Q

what two tumors are both composed of well-differentiated follicular epithelial cells?

A

follicular adenomas and carcinomas

- carcinomas are distinguished by evidence of capsular and/or vascular invasion

56
Q

what tumors are recognized based on nuclear features (ground-glass nuclei, pseudoinclusions) even in the absence of papillae?

A

papillary carcinomas

57
Q

what are a characteristic feature of papillary carcinomas?

A

psammoma bodies

- these neoplasms often metastasize by way of lymphatics, but prognosis is excellent

58
Q

what tumors are thought to arise by dedifferentiation of more differentiated neoplasms?

A

anaplastic carcinomas

59
Q

what tumors are neoplasms arisiing from the parafolicular C-cells and can occur in either sporadic (70%) or familiar (30%) settings?

A

medullary cancers

60
Q

what are the features of familial medullary thyroid cancers?

A

multicentricity and C-cell hyperplasia

61
Q

what is a characteristic hostologic finding of medullary thyroid cancer?

A

amyloid deposits

EndoRepro 2 Exam 2 (10 decks)

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