M&n Week 5: Pathology Of The Thyroid And Parathyroid

Front 1

Thyroglossal duct cysts are generally found where?

Back 1

In, or close to, the midline of the neck (near the hyoid)

Front 2

What is the most sensitive indicator of primary hypothyroidism?

Back 2

Measurement of serum TSH

Front 3

In the patient with clinical features compatible with hypothyroidism, a TSH level that is NOT elevated suggests...?

Back 3

Secondary hypothyroidism

Front 4

What can cause gestational or early infancy hypothyroidism?

Back 4

1. Nutritional lack of iodine
2. Defects in thyroid hormone synthesis

Front 5

What causes acute infective thyroiditis?

What is a symptom associated with this condition?

Back 5

Bacterior or fungal seeding of the gland

*May cause painful swelling

Front 6

Which condition results from an immune attack on the thyroid and typically follows a previous viral infection?

Back 6

Subacute granulomatous (DeQuervain's) thyroiditis

Front 7

Which condition often presents as a "flu-like" systemic illness with a sudden, painful, diffuse enlargement of the thyroid?

Is hyperthyroidism or hypothyroidism present in this condition?

Back 7

Subacute granulomatous (DeQuervain's) thyroiditis

*Results in transient thyrotoxicosis often followed by hypothyroidism

Front 8

Which type of thyroiditis clinically presents as a hard, non-tender, fixed nodule of irregular outline which may cause stridor, dysphagia, hoarseness, and dyspnea?

Back 8

Riedel's thyroiditis

(May be confused with cancer)

Front 9

Which type of thyroiditis presents as painless mild-moderate enlargement of the thyroid and/or transient hyperthyroidism which is usually self-limiting?

Back 9

Subacute or chronic lymphocytic thyroiditis

Front 10

Which gene is Hashimoto's thyroiditis associated with?

Back 10

HLA-DR5

Front 11

Which TSH-receptor autoantibodies may be produced in Hashimoto's thyroiditis?

Back 11

1. TGI (thyroid growth immunoglobulin) <--most common
2. TSI (thyroid stimulating immunoglobulin)

*Blocking antibodies for each of these may also be formed. In Hashimoto's TGI + TSI + TSI-blocking antibody)

Front 12

Which autoantibodies may be responsible for the glandular enlargement seen in Hashimoto's thyroiditis?

Back 12

TGI (thyroid growth immunoglobulin)

Front 13

Grave's disease is associated with which gene?

Back 13

HLA-DR3

Front 14

Which autoantibodies are found in Grave's disease?

Back 14

TSI and TGI
(same antibodies seen in Hashimoto's. TGI => stimulates growth of the gland, TSI => stimulates hormone production)

Front 15

Describe the classic appearance of follicular cells in Grave's disease.

Back 15

Increased numbers of tall, columnar follicular epithelial cells, creating papillary infoldings into the follicle lumen which is almost devoid of colloid material.

Front 16

What type of goiter is the result of gradual, painless enlargement of the thyroid due to compensatory hyperplasia (secondary to a defect in production or inability to secrete functional TH)?

Back 16

Diffuse nontoxic goiter

Front 17

How are multinodular goiters caused?

Back 17

End result of a long-standing diffuse nontoxic goiter

Front 18

Which type of goiter can easily be clinically confused with cancer?

Back 18

Multinodular goiter

Front 19

How does hyperthyroidism that results from multinodular goiter differ from hyperthyroidism seen in Grave's disease?

Back 19

It is not as severe as Graves' disease and not associated with ocular or skin problems

Front 20

What is the preferred mode of initial evaluation to distinguish benign from malignant thyroid tumors?

Back 20

Fine needle aspiration biopsy
(Histologic study is the only way to distinguish between benign or malignant thyroid tumors)

Front 21

The vast majority of benign thyroid neoplasms are what kind of tumors?

Back 21

Adenomas

Front 22

Almost all thyroid adenomas are derived from which cells?

Back 22

Thyroid follicular epithelial cells
(Follicular adenomas)

Front 23

Thyroid malignancies very rarely produce thyroid hormone, but they do produce which glycoprotein?

What is the significance of this?

Back 23

Thyroglobulin

*Tg can be used to monitor for post-surgical recurrence or metastases

Front 24

What type of architecture seen in thyroid lesions indicates malignancy?

Back 24

Papillary architecture

Front 25

Which thyroid carcinoma is an aggressive tumor that occurs in an older population and grows at a rapid pace?

Back 25

Undifferentiated carcinoma

Front 26

Medullary carcinomas arise from which cells?

What do these cells secrete?

Back 26

Parrafollicular ("C") cells of neural crest origin

*Calcitonin
(have ability to also secrete ACTH, protaglandins..)

Front 27

Medullary carcinonomas characteristically demonstrate deposition of what substance in the the tumor stroma?

Back 27

Amyloid
(altered calcitonin molecules)

Front 28

Although the clinical presentations vary widely, most patients with medullary carcinoma have some degree of what symptom?

Back 28

Diarrhea
(due to calcitonin or prostaglandin secretion)

Front 29

Which form of medullary carcinoma is more common--the sporadic or genetic form?

Back 29

Sporadic (75%)

Front 30

The genetic form of medullary carcinomas occur as part of which autosomal dominant syndrome?

Back 30

Multiple endocrine neoplasia syndromes

Front 31

Tumors due to the genetic form of medullary carcinomas have been shown to have a mutation in which proto-oncogene?

Back 31

RET proto-oncogene on chromosome 10

Front 32

What are the two cells of the parathyroid gland?

Back 32

1. Chief cell
2. Oxyphils

Front 33

What are the functions of PTH?

Back 33

1. Renal activation of Vitamin D
2. Increasing renal Ca2+ resporption and phosphate secretion
3. Increasing resorption from the bone stores

Front 34

Diseases of which organs may interfere with the production of active vitamin D and therefore alter calcium metabolism?

Back 34

1. Liver
2. Kidney
3. Skin?

Front 35

What sort of values is hyperparathyroidism characterized by?

Back 35

Elevated PTH levels even in the presence of:
1. Hypophosphatemia
2. Hypercalcemia
3. Increased urine Ca2+ excretion

Front 36

In the U.S., how is hyperparathyroidism usually diagnosed?

Back 36

Due to abnormal serum Ca2+ levels identified on screening serum chemistries of an asymptomatic patient.

Front 37

If hyperparathyroidism goes on undiagnosed, what sort of signs/symptoms will be observed?

Back 37

"Stones, bones, moans, and groans"

1. Stones--> nephrocalcinosis and renal stones
2. Bones--> bone demineralization (osteomalacia), osteitis fibrosa cystica, and brown tumors
3. Moans --> psychiatric disturbances, neurologic abnormalities, and muscle weakness
4. Groans--> peptic ulcers, pancreatitis, and abdominal pains

Front 38

What is the most frequent cause of primary hyperparathyroidism?

Back 38

Adenoma
(generally chief cells)

Front 39

Are parathyroid adenomas usually functional or non-functional?

Do they usually involve the superior or inferior glands?

Back 39

Almost always functional

*Inferior glands usually involved

Front 40

Which parathyroid glands tend to be more affected in primary hyperplasia?

Back 40

All four glands are affected, but the superior glands tend to be affected more prominently

Front 41

Most hyperplastic parathyroid glands show proliferation of which cell type?

Back 41

Chief cells

Front 42

What usually causes secondary hyperparathyroidism?

Back 42

Compensatory hyperplasia in response to chronic hypocalcemia and hyperphosphatemia usually due to chronic renal failure
(renal osteodystrophy)

Front 43

What sort of values is hypoparathyroidism generally characterized by?

Back 43

1. Low PTH
2. Hypocalcemia
3. Hyperphosphatemia

*However, PTH levels can be normal or high if PTH is non-functional or if there is target organ unresponsiveness

Front 44

Hypoparathyroidism is most often caused by what?

Back 44

Inadvertent removal of the parathyroids during thyroidectomy or radical neck dissection.

Front 45

What is pseudohypoparathyroidism?

What is it characterized by?

Back 45

Familial syndrome resulting from an end-organ resistance to PTH

1. High levels of PTh
2. Hypocalcemia
3. Hyperphosphatemia
4. Normal or decreased alkaline phosphatase

Front 46

Do very large parathyroid adenomas cause mass effects?

Back 46

Usually not.
Even the largest parathyroid adenomas rarely cause clinical symptomatology

Front 47

Describe the epithelial changes that occur in the thyroid follicular cells with increased activity.

Back 47

The epithelium becomes more columnar as the colloid is absorbed.

(With inactivity, the colloid accumulates, distends the follicle, and flattens the epithelium)

Front 48

List 3 major causes of hyperthyroidism.

Back 48

1. Grave's disease
2. Toxic multinodular goiter
3. Toxic adenoma

Front 49

Is subacute or chronic lymphocytic thyroiditis usually painful?

Back 49

No

Front 50

Is subacute granulomatous (DeQuervain's) thyroiditis generally painful?

Back 50

Yes
(Sudden, painful)

Front 51

Is Hashimoto's thyroiditis generally painful?

Back 51

No

Front 52

Which type of thyroiditis is generally very hard and is often confused with cancer?

Back 52

Riedel's thyroiditis

Front 53

Can patients with Hashimoto's thyroiditis experience hyperthyroidism?

Back 53

Yes
Some patients may go through a phase of hyperthyroidism before hypothyroid symptoms predominate

Front 54

What type of cells may be deficient in autoimmune thyroid diseases?

Back 54

Antigen-specific suppressor T cells

Front 55

What are some histologic features of Hashimoto's thyroiditis?

Back 55

1. Lymphocytic infiltration
2. Germinal centers
3. Hurthle cells (oncocytes)--nonfunctional follicular cells packed with mitochondria
4. Fibrosis

Front 56

What is the most common etiology of a diffuse nontoxic goiter?

Back 56

Endemic goiter
(Iodine deficiency)

Front 57

Describe the development of a diffuse nontoxic goiter.

Back 57

1. HYPERPLASTIC STAGE: TSH stimulates increased follicular cell activity --> increased cell mass and tall columnar epithelium; depleted colloid follicles

2. COLLOID INVOLUTION: As euthyroid state is reached, colloid accumulates unevenly and flattens the epithelium

Front 58

List the 4 criteria for classification of an adenoma.

Back 58

1. Complete fibrous encapsulation of the nodule
2. Compression of adjacent thyroid parenchyma
3. Different histologic appearance than normal tissue
4. Lack of multinodularity in the remainder of the gland

Front 59

What are the characteristic nuclear changes seen in papillary adenocarcinoma?

Back 59

Ground glass, or optically clear nuclei ("orphan annie eyes")

(psammoma bodies are another useful histologic feature)

Front 60

What type of thyroid carcinoma is the most common?

Back 60

Papillary adenocarcinoma

Front 61

Which type of thyroid carcinoma tends to show central fibrosis and areas of necrosis, hemorrhage, and cyst formation?

Back 61

Follicular carcinoma

Front 62

Why is it necessary to distinguish between parathyroid adenoma and primary hyperplasia as the cause for hyperparathyroidism?

Back 62

Etiology has therapeutic implications:
Surgical incision of an adenoma should be curative
Surgical excision of a single hyperplastic gland, however, is not curative due to the persistent activity of remaining glands.

Front 63

How should primary parathyroid hyperplasia be treated?

Back 63

With removal of 3 or 3 1/2 glands