Thyroid Pathology BMS 200

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Questions and Answers

What is the primary pathological finding in Hashimoto's thyroiditis?

Lymphocytic infiltration with atrophy of follicles (correct)

Calcification of the thyroid tissue

Excessive secretion of thyroid hormones

Hyperplasia of the thyroid follicles

In Hashimoto's thyroiditis, which type of cells is primarily involved in mediating damage to the thyroid?

B cells

Cytotoxic T-cells (correct)

Natural killer cells

Helper T-cells

Which of the following HLA haplotypes is NOT associated with Hashimoto's thyroiditis?

HLA-DR5

HLA-DR3

HLA-B27 (correct)

HLA-DR4

What role do anti-thyroid antibodies play in Hashimoto’s thyroiditis?

They are diagnostically useful, but not primarily damaging Signup and view all the answers

Which condition is commonly associated with Hashimoto's thyroiditis?

Type 1 diabetes mellitus Signup and view all the answers

Which autoimmune condition is characterized by the destruction of thyroid tissue leading to hypothyroidism?

Hashimoto’s thyroiditis Signup and view all the answers

What is a common consequence of untreated hyperthyroidism, especially in the context of Graves disease?

Thyroid storm Signup and view all the answers

Which of the following conditions is NOT associated with hyperthyroid states?

Hashimoto’s thyroiditis Signup and view all the answers

What is the primary pathophysiological effect of iodine deficiency on thyroid function?

Development of goiter Signup and view all the answers

Which of the following theories does NOT explain the pathogenesis of autoimmune thyroid diseases?

Hormonal balance theory Signup and view all the answers

Myxedema is primarily associated with which thyroid condition?

Severe hypothyroidism Signup and view all the answers

What underlying factor is common in both Graves disease and toxic multinodular goiter?

Autonomous thyroid hormone production Signup and view all the answers

Clinical features of hypothyroidism may include which of the following?

Bradycardia Signup and view all the answers

Which clinical feature is most commonly associated with Hashimoto's thyroiditis?

Fatigue and cold intolerance Signup and view all the answers

What cardiovascular symptom is frequently seen in patients with Hashimoto's thyroiditis?

Mild hypotension Signup and view all the answers

Which neurological symptom is characteristic of Hashimoto's thyroiditis?

Paresthesias Signup and view all the answers

What is a common skin manifestation of Hashimoto's thyroiditis?

Myxedema Signup and view all the answers

Subacute thyroiditis can be caused by which of the following viruses?

SARS-CoV-2 Signup and view all the answers

What is the typical thyroid examination finding in subacute thyroiditis?

Tender on palpation Signup and view all the answers

Which phase of Hashimoto's thyroiditis is characterized by excessive thyroid hormone release?

Thyroxic phase Signup and view all the answers

Which reproductive symptom may occur in Hashimoto's thyroiditis?

Menorrhagia Signup and view all the answers

What characterizes the pathology of subacute thyroiditis in its early stages?

Multi-nucleate giant cells Signup and view all the answers

What gastrointestinal symptom is often observed in Hashimoto's thyroiditis?

Constipation Signup and view all the answers

What is a complication of long-term hypothyroidism that occurs alongside another precipitating factor?

Myxedema coma Signup and view all the answers

Which of the following is NOT a clinical feature of myxedema coma?

Tachycardia Signup and view all the answers

Which statement correctly describes the role of TRH in thyroid hormone production?

Low T3 and T4 levels increase TRH secretion. Signup and view all the answers

In myxedema coma, which cardiovascular feature is often observed?

Maintenance of elevated diastolic pressure Signup and view all the answers

Which respiratory complication is associated with myxedema coma?

Hypoventilation due to carbon dioxide insensitivity Signup and view all the answers

What condition is characterized by mental and physical developmental delays due to thyroid hormone deficiency during growth?

Cretinism Signup and view all the answers

Which gastrointestinal symptom can be associated with myxedema coma?

Ileus Signup and view all the answers

What is a common renal change seen in patients with myxedema coma?

Hyponatremia Signup and view all the answers

What does the term 'myxedema' often refer to in a clinical context?

Non-pitting edema in hypothyroid dermopathy Signup and view all the answers

Which of the following medications can potentially precipitate myxedema coma?

Various medications Signup and view all the answers

What is the most common type of thyroid neoplasm?

Follicular adenoma Signup and view all the answers

What percentage of thyroid cancers is accounted for by papillary carcinoma?

70 - 80% Signup and view all the answers

Which type of thyroid carcinoma is derived from calcitonin-secreting C-cells?

Medullary carcinoma Signup and view all the answers

What is a distinguishing factor between hyperplasia and neoplasia?

Neoplasia grows despite the absence of external stimuli. Signup and view all the answers

What is the survival outlook for patients diagnosed with early-stage papillary carcinoma?

Minimal impact on mortality rates. Signup and view all the answers

In which regions of the world is follicular carcinoma more prevalent?

Iodine-deficient regions Signup and view all the answers

How can TSH suppression therapy affect well-differentiated thyroid tumors?

It can suppress tumor activity. Signup and view all the answers

What characteristic of follicular carcinoma complicates its diagnosis?

It often looks similar to non-malignant adenomas. Signup and view all the answers

What external factor significantly worsens the prognosis of follicular carcinoma?

Distant metastasis to sites like bone and lung. Signup and view all the answers

What type of thyroid cancer has the greatest risk of metastasis when angioinvasion occurs?

Papillary carcinoma Signup and view all the answers

Which statement correctly differentiates toxic multinodular goitre from toxic adenoma?

Toxic multinodular goitre involves multiple autonomous nodules, while toxic adenoma is characterized by a single nodule. Signup and view all the answers

What general clinical feature is least likely associated with toxic multinodular goitre in elderly patients?

Severe weight gain Signup and view all the answers

In the context of thyrotoxicosis, which laboratory finding is most indicative of toxic multinodular goitre?

Low TSH and normal T4 levels Signup and view all the answers

Which scenario is most likely to trigger a thyroid storm?

An acute illness in a patient previously diagnosed with hyperthyroidism Signup and view all the answers

What distinguishes the pathogenesis of toxic multinodular goitre from non-toxic multinodular goitre?

Autonomous nodules in toxic multinodular goitre produce thyroid hormones independently of TSH. Signup and view all the answers

Which thyroid cancer type is characterized by rapid metastases and a poor prognosis?

Anaplastic thyroid cancer Signup and view all the answers

What is the mechanism of action of methimazole in the treatment of thyroid conditions?

Inhibits thyroid peroxidase activity Signup and view all the answers

Which genetic mutation is commonly found in poorly differentiated thyroid cancers?

All of the above Signup and view all the answers

What is the reason for preferring methimazole over propylthiouracil (PTU) in clinical practice?

Methimazole has less associated liver toxicity. Signup and view all the answers

Which of the following factors is a recognized risk factor for developing thyroid cancer?

Exposure to radioactive isotopes Signup and view all the answers

What hormone is primarily secreted by medullary thyroid carcinoma derived from C-cells?

Calcitonin Signup and view all the answers

In the context of thyroid neoplasms, RET mutations are most commonly found in which type?

Papillary thyroid carcinoma Signup and view all the answers

Which TSH receptor pathway is commonly activated in differentiated thyroid cancers?

MAPK signaling pathway Signup and view all the answers

What is the impact of iodine deficiency on thyroid hormone levels?

Decreased production of T3 and T4 due to insufficient synthesis Signup and view all the answers

Which autoimmune mechanism is hypothesized to contribute to the pathogenesis of Graves disease?

Production of IgG antibodies against TSH receptors Signup and view all the answers

Thyroid storm is most closely associated with which of the following clinical features?

Severe agitation and confusion Signup and view all the answers

What is a significant complication of congenital hypothyroidism if left untreated?

Cognitive impairment and growth delays Signup and view all the answers

What is the consequence of low levels of T3 and T4 in the body?

Increased secretion of TRH Signup and view all the answers

Which mechanism is involved in the pathogenesis of Hashimoto’s thyroiditis?

Direct cytotoxic effects of CD4+ T cells on thyroid follicles Signup and view all the answers

What role does T3 play compared to T4 in the context of thyroid hormone activity?

T3 is the more active form of thyroid hormone Signup and view all the answers

Which of the following factors can precipitate myxedema coma?

Infection Signup and view all the answers

In subacute thyroiditis, which viral agent is often implicated?

Mumps virus Signup and view all the answers

Toxic multinodular goiter is primarily characterized by which mechanism of hormone production?

Autonomous production by hyperfunctioning nodules independent of TSH regulation Signup and view all the answers

How do cardiac changes manifest in patients with myxedema coma?

Hypotension with elevated peripheral vascular resistance Signup and view all the answers

Which neurologic symptom is typically observed in myxedema coma?

Slow progression from lethargy to coma Signup and view all the answers

Which of the following statements about thyroid cancers is correct?

Medullary carcinoma develops from C-cells and secretes calcitonin Signup and view all the answers

What gastrointestinal symptom is frequently associated with myxedema coma?

Constipation Signup and view all the answers

Which thyroid neoplasm is most common among non-malignant tumors?

Follicular adenoma Signup and view all the answers

Which renal change can occur in patients with myxedema coma?

Hyponatremia due to water retention Signup and view all the answers

In the setting of myxedema coma, which respiratory complication is commonly observed?

Obstructive sleep apnea from macroglossia Signup and view all the answers

What characterizes well-differentiated tumours like follicular and papillary carcinoma in terms of TSH suppression therapy?

They respond somewhat to TSH suppression therapy. Signup and view all the answers

Which type of thyroid carcinoma has the highest prevalence in populations with iodine deficiency?

Follicular carcinoma Signup and view all the answers

What differentiates myxedema from myxedema coma in clinical terminology?

Myxedema describes the non-pitting edema in hypothyroid patients Signup and view all the answers

What distinguishes the incidence of myxedema coma among different populations?

It predominantly affects elderly hypothyroid patients Signup and view all the answers

What histological feature is typical of papillary carcinoma?

Cells with large, clear nuclei in papillary structures Signup and view all the answers

Which characteristic defines neoplasia in contrast to hyperplasia?

Growth occurs despite the absence of external stimuli. Signup and view all the answers

Which thyroid cancer type is most commonly associated with angioinvasion and increased metastasis risk?

Papillary carcinoma Signup and view all the answers

What is true regarding the prognosis of follicular carcinoma?

Prognosis worsens with vascular invasion and metastasis. Signup and view all the answers

What is the most common endocrine malignancy based on annual incidence?

Papillary carcinoma Signup and view all the answers

Which subgroup of papillary carcinoma has an increased risk of metastasis?

Poorly differentiated papillary carcinoma Signup and view all the answers

What type of thyroid carcinoma arises from calcitonin-secreting C-cells?

Medullary carcinoma Signup and view all the answers

Study Notes

Thyroid Pathology Overview

Goiter formation can occur in both hyperthyroidism (excess hormone production) and hypothyroidism (deficient hormone production).
Clinical features of over-section of thyroid hormones include thyrotoxicosis, weight loss, and increased heart rate; under-section can lead to fatigue, weight gain, and bradycardia.
Iodine deficiency is a major cause of hypothyroidism, leading to decreased thyroid hormone production and compensatory goiter formation.

Autoimmune Thyroid Diseases

Hashimoto’s thyroiditis: Common endocrine disorder; incidence is ~4/1000 women and 1/1000 men annually.
Pathological features include lymphocytic infiltration, germinal center formation, thyroid follicle atrophy, and loss of colloid. Progression can lead to atrophic thyroiditis, with increased fibrosis and limited lymphocyte infiltration.
Genetic susceptibility linked to HLA haplotypes (HLA-DR3, DR4, DR5) and associated with other autoimmune diseases (Type 1 diabetes, Addison’s disease).
Damage primarily mediated by cytotoxic T-cells and local inflammatory cytokines (e.g., TNF, IL-1, IFN-gamma); anti-thyroid antibodies (anti-TPO, anti-thyroglobulin) are diagnostically useful.

Clinical Features of Hashimoto’s Thyroiditis

Symptoms include fatigue, cold intolerance, myxedema (thickened skin), hoarseness, and carpal tunnel syndrome.
Cardiovascular effects: Bradycardia, mild hypotension, hypercholesterolemia; severe cases can lead to congestive heart failure and pericardial effusion.
Neurological impacts manifest as paresthesias and delayed reflexes; respiratory issues may involve hypoventilation.
Reproductive complications can include menstrual irregularities and erectile dysfunction in men.

Subacute Thyroiditis

Known as de Quervain’s thyroiditis; often follows viral infections (e.g., mumps, influenza).
Pathological findings show multinucleate giant cells and varying degrees of lymphocytic infiltration.
Clinical features can include transient thyrotoxicosis, neck pain, and tenderness of the thyroid gland.
Symptoms may fluctuate between hypothyroidism and thyrotoxicosis based on the disease phase.

Myxedema Coma

A severe complication of untreated hypothyroidism, often precipitated by stressors (infection, trauma).
Clinical presentation includes hypotension, bradycardia, lethargy, and hypothermia.
Neurological symptoms can progress to confusion, severe depression, and potential seizures.
Respiratory issues may involve hypoventilation and sleep apnea.
Gastrointestinal findings may include ileus and constipation, while renal effects include hyponatremia.

Thyroid Neoplasms

Incidence of thyroid cancer is 15 per 100,000 per year, making it the most common endocrine malignancy.
Most common types:
- Papillary carcinoma (70-80%): Well-differentiated with a high survival rate; presents with clear nuclei and papillary structures.
- Follicular carcinoma (5-10%): More common in iodine-deficient regions; difficult to differentiate from adenomas without invasive characteristics.
- Medullary carcinoma: Derived from calcitonin-secreting C-cells.
- Anaplastic carcinoma: Highly aggressive with poor prognosis.
Thyroid adenomas: Non-malignant tumors, often asymptomatic, with a prevalence of up to 5% in the population.

Treatment Mechanisms

Anti-thyroid medications target hyperthyroidism by inhibiting hormone production; levothyroxine replaces deficient hormone in hypothyroidism.
TSH suppression therapy may be useful for well-differentiated tumors like follicular and papillary carcinoma.

Thyroid Pathology Overview

Hypothyroidism involves reduced thyroid function with various causes, including autoimmune conditions, iodine deficiency, and iatrogenic factors.
Hyperthyroidism can result from Graves' disease, toxic multinodular goiter, or thyroid neoplasms (follicular, papillary, medullary, anaplastic carcinomas).

Goiter Formation

Goiter develops due to increased TRH and TSH secretion in response to low T3 and T4 levels in hypothyroidism, or due to excessive secretion of thyroid hormones in hyperthyroidism.

Myxedema and Myxedema Coma

Myxedema coma is a severe complication of prolonged hypothyroidism exacerbated by additional stressors (e.g., infection, trauma).
Characteristics include lethargy and slowed neurological progression, hypoventilation, and gastrointestinal symptoms like ileus and constipation.
Cardiovascular features include hypotension, bradycardia, and dangerous dysrhythmias (e.g., heart block).

Thyroid Storm

Thyroid storm is a life-threatening hyperthyroidism exacerbation, typically triggered by acute illnesses in previously hyperthyroid patients.
Symptoms include high fever, tachycardia, altered mental status, and increased systemic demands for thyroid hormones.

Thyroid Neoplasms

Benign adenomas, especially follicular adenomas, are common, while malignant cancers include papillary (70-80%), follicular (5-10%), medullary, and anaplastic carcinomas.
Papillary carcinoma is the most prevalent, characterized by well-differentiated cells and a good prognosis.
Anaplastic carcinoma is aggressive with a poor survival rate, typically less than 6 months post-diagnosis.

Genetic Factors

Activating mutations in the TSH receptor (and RAS, RET signaling pathways) are frequently observed in thyroid cancers.
p53 mutations are common in poorly differentiated cancers, indicating a more aggressive disease course.

Clinical Features of Thyroid Conditions

Toxic multinodular goiter presents with mild to subclinical hyperthyroidism and is more common in elderly patients; associated symptoms may include palpitations and weight loss.
Congenital hypothyroidism can lead to developmental delays (cretinism) and is linked to a higher prevalence of other congenital malformations.

Pharmacological Treatment

Propylthiouracil (PTU) and methimazole are anti-thyroid medications that inhibit thyroid hormone synthesis. PTU additionally affects T4 to T3 conversion.
Levothyroxine is used for hypothyroidism treatment, primarily as a synthetic T4.

Autoimmune Thyroid Diseases

Autoimmune conditions like Graves' and Hashimoto's can be influenced by factors like gut-thyroid axis interactions, infectious triggers, pregnancy, and environmental pollutants.

Relationship Between Infections and Thyroiditis

Viral infections may contribute to thyroiditis, leading to autoimmune responses that affect hormone production and regulation.

Iodine Deficiency

Iodine deficiency can directly result in hypothyroidism by impairing thyroid hormone synthesis, leading to compensatory hyperplasia and goiter formation.

Complications of Thyroid Disorders

Over-secretion of thyroid hormones can lead to thyrotoxicosis, while inadequate secretion contributes to myxedema coma, both presenting distinct clinical challenges and management issues.

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Description

This quiz covers key concepts regarding thyroid pathology, including the formation of goiter in hyperthyroidism and hypothyroidism. It also addresses clinical features associated with abnormal thyroid hormone levels and delves into the pathophysiology of autoimmune thyroid diseases such as Graves' and Hashimoto's. Explore the implications of iodine deficiency and various theories of pathogenesis.