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Robbins systemic pathology > Chapter 24: Endocrine > Flashcards

Chapter 24: Endocrine Flashcards

1
Q

Define microadenoma of the pituitary

A

<1 cm

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2
Q

Features of diabetes insipidus

A
  • deficiency of ADH
  • inability of kidney to reabsorb water -> polyuria
  • causes: head trauma, tumors, etc (central)
  • nephrogenic results from non-responsiveness of renal tubules to circulating ADH
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3
Q

Features of SIADH

A
  • hyponatremia from excessive water reabsorption with cerebral edema
  • causes: ectopic ADH from non-pituitary tumors, drugs, CNS disorders
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4
Q

Two variants of craniopharyngioma

A

Adamantinomatous: usually children
-stratified squamous epithelium with peripheral palisading in a spongy reticulum with wet keratin formation
-dystrophic calcs, fibrosis, cyst formation
Papillary: usually adults
-sheets and papillae of squamous epithelium
-usually no calcs, keratin or cysts
-no peripheral palisading

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5
Q

Cardiac effects of hyperthyroidism

A

Palpitations and arrhythmia (esp. A fib)

Myocardial lymphocytes and eosinophils with fibrosis and fatty infiltration, sometimes resulting in LV dysfunction

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6
Q

What is cretinism?

A
  • congenital/early childhood hypothyroidism
  • less common with supplementation of iodine
  • impaired CNS and skeletal development
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7
Q

Pathogenesis of Hashimoto thyroiditis

A
  • loss of self-tolerance to thyroid autoantigens
  • patients have circulating anti-thyroglobulin and thyroid peroxidase antibodies
  • CD8 cytotoxic cell death and cytokine mediated cell death in addition to antibody mediated effects
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8
Q

Etiology of subacute (granulomatous/deQuervain) thyroiditis

A

Viral trigger usually

-stimulation of cytotoxic T cells that attack thyroid follicular cells

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9
Q

Histology of subacute thyroiditis

A
  • patchy involvement of the gland
  • early: neutrophilic destruction of follicles
  • later: lymphocytes, macrophages, giant cells and granulomas
  • even later: fibrosis
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10
Q

Biochemical/radioactive iodine findings in subacute thyroiditis?

A

Increased T3 and T4 and decreased TSH

Decreased uptake of radioactive iodine

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11
Q

Histologic findings of Graves disease

A
  • diffuse hypertrophy and hyperplasia of follicular cells
  • tall, crowded follicular cells, sometimes forming micropapillae
  • pale, scalloped colloid
  • lymphoid infiltrates and germinal centres
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12
Q

Features associated with higher likelihood of a thyroid nodule being neoplastic

A
  • younger age
  • history of radioactive iodine
  • male gender
  • solitary nodule
  • cold nodules more likely malignant than hot nodules
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13
Q

Pathogenesis of follicular thyroid carcinoma

A

PI3/AKT signalling pathway mutations

  • includes RAS gain of function and PTEN loss of function
  • end result is activating of oncogenic pathway

t(2;3) found in some follicular carcinomas: PAX-PPARG fusion gene

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14
Q

Special features of tall cell variant of PTC

A
  • older patients, more aggressive
  • most have BRAF mutations, some with RET/PTC translocations in addition, which may account for more aggressive behaviour
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15
Q

Special features of the diffuse sclerosing variant of PTC

A
  • younger patients including children
  • papillary growth but with extensive fibrosis
  • no BRAF mutations; some have RET/PTC
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16
Q

Histologic features of follicular thyroid carcinoma

A
  • often well circumscribed proliferations of small follicles with or without colloid
  • sometimes Hurthle cell dominant
  • vascular invasion: either in or outside the capsule
  • capsular invasion
  • no nuclear features of PTC
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17
Q

What are the contents of oxyphil and chief cells?

A

Chief cells: parathyroid hormone secretory granules

Oxyphil cells: mitochondria and glycogen granules but no PTH granules

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18
Q

Functions of parathyroid hormone

A
  • increased gut absorption of calcium
  • increases renal conversion of Vit D to its active form
  • increases renal reuptake of calcium
  • increases urinary phosphate excretion
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19
Q

Causes of primary hyperparathyroidism and their frequencies

A

Adenoma (85%)
Hyperplasia (5-10%)
Carcinoma (1%)

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20
Q

Familial syndromes with primary hyperparathyroidism

A

MEN1: 11q13; both adenomas and hyperplasias
-mutations in MEN1 can also be found in sporadic adenomas
MEN2A: RET mutations chr 10
Familial hypocalciuric hypercalcemia::
-inactivating mutations in calcium sensing receptor gene (CASR) (3q)

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21
Q

Molecular defects identified in sporadic parathyroid adenomas

A

CyclinD1

MEN1

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22
Q

Features of parathyroid adenoma

A
  • 0.5-5 gm
  • other glands are normal weight
  • peripheral rim of normal thyroid tissue
  • may see endocrine atypia but usually no mitoses
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23
Q

Pathologic features of parathyroid carcinoma

A
  • may exceed 10 gm in weight
  • usually uniform cells often not distinguishable from adenoma
  • diagnosis of malignancy rests of invasion of surrounding tissues and metastasis
24
Q

Extra-parathyroid manifestations of hyperparathyroidism

A

Osteitis fibrosa cystica: thinned bone cortex with marrow replaced by cysts and fibrosis due to increased osteoclastic activity
Brown tumors
Nephrolithiasis
Metastatic calcification in other tissues

25
Q

Cause of secondary hyperparathyroidism?

A

Usually, chronic renal failure
-impaired urinary phosphate excretion leads to hyperphosphatemia that depresses serum calcium levels and thereby increases PTH secretion

26
Q

Tertiary hyperparathyroidism?

A

Parathyroid activity becomes autonomous such that it doesn’t require stimulation from low serum calcium to produce PTH. May require parathyroidectomy.

27
Q

Product and function of pancreatic alpha cells?

A

Glucagon secretion

Causes hyperglycemia

28
Q

Product and function of pancreatic delta cells?

A

Somatostatin secretion

Inhibits both insulin and glucagon release

29
Q

What cell types secrete VIP and serotonin, respectively?

A

VIP: D1 cells
Serotonin: Enterochromaffin cells

30
Q

Main pathology of type I diabetes

A
  • destruction of beta cells resulting in absolute lack of insulin
  • loss of self-tolerance with putative antigens being insulin, glutamic acid decarboxylase, and islet cell autoantigen 512
31
Q

Main pathology of type II diabetes

A
  • peripheral resistance to insulin action and an inadequate response by beta cells (relative insulin deficiency)
  • no autoimmune factors have been implicated in the pathogenesis
32
Q

Genetic factors in type I DM

A

HLA type, especially DR3 and DR4

-other implicated genes include ‘insulin’, CTLA4 and PTPN22

33
Q

Which probably has a larger genetic contribution, type I or type II DM?

A

Probably type II, with higher concordance in monozygotic twins

34
Q

Factors by which obesity negatively influences insulin resistance

A
  • adipokines
  • nonesterified fatty acids
  • inflammation
  • peroxisome-proliferator activated receptor gamma
35
Q

Monogenic causes of diabetes

A
  • genetic defects in beta cell function (MODY; 6 different genes have been implicated)
  • genetic defects in insulin action (mutations of the insulin receptor)
36
Q

Metabolic pathways implicated in the deleterious effects in diabetes

A
  • formation of advanced glycation end products: causes inflammation, ROS production, proliferation of vascular smooth muscle and procoagulant effects
  • activation of protein kinase C: pro-angiogenic, pro-fibrogenic, and pro-inflammatory effects
  • intercellular hyperglycemia and disturbances in polyol pathways
37
Q

Macrovascular disease in diabetes

A
  • results from endothelial dysfunction

- accelerated atherosclerosis: myocardial infarction, gangrene of extremities

38
Q

Other systemic changes in DM

A
  • hyaline arteriolosclerosis (also associated with hypertension, but more prevalent in diabetics)
  • diabetic microangiopathy (basement membrane thickening with leaky capillaries: underlies diabetic retinopathy, nephropathy and neuropathy
39
Q

Features of diabetic nephropathy

A
  • glomerular lesions
  • vascular lesions (hyaline arteriolosclerosis)
  • pyelonephritis and papillary necrosis
40
Q

Features of glomerular lesions in DM

A
  • diffuse mesangial matrix increase
  • diffuse basement membrane thickening
  • nodular glomerulosclerosis (Kimmelstiel-Wilson nodules, PAS positive) with fibrin caps (in capillary loops) and capsular drops (adherent to Bowman’s capsule)
41
Q

Most common causes of mortality in DM?

A

Myocardial infarction, renal insufficiency, cerebrovascular accidents

42
Q

Features of gastrinoma

A
  • over 50% malignant
  • may arise in duodenum, pancreas or peripancreatic soft tissues
  • produce ZE syndrome: pancreatic tumor, gastric acid hypersecretion and peptic ulceration
  • 25% associated with MEN1
43
Q

What is the gross feature of adrenal glands in Cushing disease?

A

Nodular cortical hyperplasia

44
Q

Features of adrenal carcinomas

A
  • more often functional than adenomas; often associated with virilization
  • large, invasive tumors
  • variegated, hemorrhagic and necrotic cut surface
  • may be well differentiated or composed of monster cells
45
Q

Features of MEN1

A
  • hyperparathyroidism: both adenomas and hyperplasias
  • pancreatic endocrine tumors
  • pituitary adenomas (prolactinoma most common)

-also, duodenal gastrinomas, carcinoid tumors, thyroid and adrenal adenomas, lipomas

46
Q

What is the mutation in MEN1

A
  • germline mutation in MEN1 (menin)

- normal menin activates some cell cycle inhibitors such as p16

47
Q

What syndromes are associated with pituitary tumors?

A

Carney complex (PRKAR1A)
Pituitary adenoma predisposition syndrome (mutations of AIP)
MEN1 (menin)
MEN1-like syndrome (CDKN1B/p27)

48
Q

What are features of autoimmune polyendocrine syndromes types 1 and 2?

A

APS1: mutations in autoimmunre regulator gene (AIRE)
-autoimmune hypoparathyroidism, mucocutaneous candidiasis, primary adrenal insufficiency, idiopathic hypogonadism, pernicious anemia and ectodermal dysplasia; absence of AIRE compromises central tolerance to peripheral antigens, resulting in autoimmunity
APS2: adrenal insufficiency and autoimmune thyroiditis without other signs of ASP1 (more common, more heterogenous genetically)

49
Q

What are candidate genes for type 2 DM?

A
  • TCF7L2
  • PPARG
  • FTO
50
Q

What are the main causes of primary hyperaldosteronism?

A
  • idiopathic bilateral (most common)
  • adrenocortical adenoma or carcinoma
  • glucocorticoid remediable hyperaldosteronism due to ACTH (rare)
51
Q

What are clinical features of hyperaldosteronism?

A
  • hypertension

- hypokalemia (causing weakness, paesthesia, visual disturbance, tetany)

52
Q

What’s the most common enzyme deficiency in congenital adrenal hyperplasia?

A

21 hydroxylase deficiency; may have salt wasting forms or simple virilizing forms
-adrenals are hyperplastic because of stimulation by ACTH, but glucocorticoids can’t be made

53
Q

What are most common causes of primary chronic adrenocortical insufficiency?

A
  • autoimmune adrenalitis (60-70%), due to autoantibodies to steroidogenic enzymes
  • tuberculosis
  • AIDS
  • metastatic cancer
54
Q

What are clinical features of Addison disease?

A
  • weakness and fatigability
  • GI distrubances
  • hyperpigmentation due to increased levels of POMC (a precursor of ACTH - not seen in adrenocortical insufficiency caused by a primary pituitary or hypothalamic disease)
  • hyperkalemia
  • hyponatremia
  • volume depletion
  • hypotension
55
Q

What underlying pathogenic mechanism do the SDHB C and D syndromes and VHL have in common?

A

All probably lead to stabilization of HIF1 alpha

56
Q

What is catecholamine cardiomyopathy?

A
  • a consequence of paroxysms of hypertension seen in pheochromocytoma
  • acute CHF, pulmonary edema, myocardial infarction, arrhythmia, etc.

Robbins systemic pathology (17 decks)

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