Podcast
Questions and Answers
What age group is Hashimoto’s thyroiditis most commonly diagnosed in?
What age group is Hashimoto’s thyroiditis most commonly diagnosed in?
Which of the following laboratory findings is usually associated with Hashimoto’s thyroiditis?
Which of the following laboratory findings is usually associated with Hashimoto’s thyroiditis?
In which percentage of patients does Hashimoto’s thyroiditis present with hyperthyroidism?
In which percentage of patients does Hashimoto’s thyroiditis present with hyperthyroidism?
What is a rare but recognized complication of chronic autoimmune thyroiditis?
What is a rare but recognized complication of chronic autoimmune thyroiditis?
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What is the primary mechanism by which hypothyroidism occurs in Hashimoto's thyroiditis?
What is the primary mechanism by which hypothyroidism occurs in Hashimoto's thyroiditis?
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What treatment is typically indicated for overtly hypothyroid patients?
What treatment is typically indicated for overtly hypothyroid patients?
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Which of the following antibodies are commonly associated with Hashimoto's thyroiditis?
Which of the following antibodies are commonly associated with Hashimoto's thyroiditis?
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Which histological feature is typically observed in Hashimoto's thyroiditis during microscopic examination?
Which histological feature is typically observed in Hashimoto's thyroiditis during microscopic examination?
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What role do CD4+ T lymphocytes play in the pathogenesis of Hashimoto's thyroiditis?
What role do CD4+ T lymphocytes play in the pathogenesis of Hashimoto's thyroiditis?
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Which of the following factors is NOT associated with an increased risk of Hashimoto's thyroiditis?
Which of the following factors is NOT associated with an increased risk of Hashimoto's thyroiditis?
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Study Notes
Overview of Lymphocytic (Hashimoto’s) Thyroiditis
- Hashimoto's thyroiditis, known as struma lymphomatosa, was first described in 1912 by Hakuro Hashimoto.
- It represents the most common inflammatory disorder of the thyroid and is the leading cause of hypothyroidism today.
Etiology, Pathogenesis, and Pathology
- An autoimmune process initiated by activated CD4+ T lymphocytes targeting thyroid antigens leads to the disease.
- Cytotoxic CD8+ T cells are recruited to the thyroid, causing damage.
- Hypothyroidism arises from the destruction of thyrocytes by T cells and from autoantibodies that fix complement or block TSH receptors.
- Major autoantibodies target three antigens:
- Thyroglobulin (Tg) - 60%
- Thyroid peroxidase (TPO) - 95%
- TSH receptor (TSH-R) - 60%
- Sodium/iodine symporter - 25%
- Apoptosis is implicated in the disease's development.
- Environmental factors, including increased iodine intake and medications like interferon-α, lithium, and amiodarone, may trigger the condition.
- There is a familial predisposition to thyroid autoantibodies in first-degree relatives of affected individuals.
- Specific chromosomal abnormalities, such as Turner’s syndrome and Down syndrome, are associated with higher incidence of autoantibodies and hypothyroidism.
- Genetic associations include HLA-B8, DR3, and DR5 haplotypes, as well as alterations in the CTLA4 gene and various cytokine genes.
Gross and Microscopic Findings
- The thyroid gland presents as mildly enlarged with a pale, gray-tan granular cut surface.
- Microscopic examination reveals diffuse infiltration of small lymphocytes and plasma cells, with occasional germinal centers.
- Thyroid follicles are reduced in size, have diminished colloid, and increased interstitial connective tissue.
- Follicles may be lined by Hürthle or Askanazy cells, characterized by abundant eosinophilic granular cytoplasm.
Clinical Presentation
- More prevalent in women (male-to-female ratio of 1:10 to 20) aged 30 to 50.
- Common presentations include painless anterior neck mass or firm, enlarged gland found during routine exam.
- 20% of patients may present with hypothyroidism; 5% may experience hyperthyroidism (Hashitoxicosis).
- Physical exams often reveal a diffusely enlarged, lobulated gland, sometimes with an enlarged pyramidal lobe.
Diagnostic Studies
- Diagnosis is confirmed with elevated TSH levels and the presence of thyroid autoantibodies.
- Fine needle aspiration biopsy (FNAB) with ultrasound guidance is warranted for solitary suspicious nodules or rapidly enlarging goiters.
- Chronic autoimmune thyroiditis may lead to thyroid lymphoma, present at a prevalence 80 times higher than in the general population.
Treatment
- Thyroid hormone replacement therapy is critical for overt hypothyroid patients to maintain normal TSH levels.
- Management of subclinical hypothyroidism remains controversial; treatment may be indicated for those with cardiovascular risk factors or in special populations like pregnant women.
- Surgical intervention may be needed for suspected malignancy or in cases of compressive symptoms from enlarged goiters.
Riedel’s Thyroiditis
- Riedel’s thyroiditis, also known as invasive fibrous thyroiditis, is a rare variant characterized by replacement of thyroid tissue with fibrous tissue.
- The etiology of Riedel’s thyroiditis remains controversial.
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Description
This quiz explores Lymphocytic (Hashimoto's) Thyroiditis, first described by Hashimoto in 1912. It discusses its etiology, pathogenesis, and pathology, highlighting its significance as the most common inflammatory disorder of the thyroid and a leading cause of hypothyroidism. Test your knowledge on the autoimmune processes involved and the role of CD4+ T lymphocytes.
