Pathology 🩺 Flashcards
what are thyroid gland disorders?
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Functional disorders:
- Hyperthyroidism (thyrotoxicosis and thyroid storm)
- Hypothyroidism (cretinism, myxedema) - Thyroiditis
- Goiter
- Neoplasms
what are the causes of hyperthyrodism?
Primary:
- Graves disease
- Toxic multinodular goiter
- Toxic follicular thyroid adenoma
Secondary “in parts rather than the thyroid gland”
- TSH-secreting pituitary adenoma
what are the causes of hypothyrodism?
Primary:
- Iodine deficiency “people leaving away from seas”
- Hashimoto thyroiditis
- Postablative
- Genetic defects in thyroid develpment
- Dyshormonogenetic goiter.
- Thyroid hormone resistance
Secondary:
- Pituitary failure.
Incidence of Hashimoto Thyroiditis
- The most common cause of Hypothyroidism after iodine deficiency.
- More common in females
Pathogenesis of Hashimoto Thyroiditis
“inhibit thyroglubulin & oxidation of iodide”
- Auto-immune thyroiditis
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- Activation of helper (CD4+) T lymphocytes sensitized to thyroid antigens:
a) CD4+ helper T lymphocytes stimulate proliferation of cytotoxic (CD8+) T lymphocytes, which attack thyroid follicular cells.
b) CD4+ helper T lymphocytes T lymphocytes also recruit reactive B lymphocytes to produce antibodies against thyroid antigens as anti-thyroglobulin and anti-thyroid peroxidase.
Gross appearence of Hashimoto Thyroiditis
“enlarged,firm & loss of glistening app. + late atrophy”
Early: symmetrical diffuse enlargement of the thyroid gland with vague nodularity
a) The affected areas are white gray or yellow brown and firm
b) They lack the glistening appearance of colloid
Late: The gland becomes symmetrically atrophic
Microscopic appearence of Hashimoto Thyroiditis
“lymphocytes + Hurthe cells”
- follicles are atrophied.
- Follicles are lined by large cubical cells with eosinophilic granular cytoplasm (Hurthle cells).
- Inflammatory cells (lymphocytes, plasma cells, macrophages).
- Reactive lymphoid follicles.
what are the complications of Hashimoto Thyroiditis?
- Hypothyroidism
- Neoplasms (papillary thyroid carcinoma, lymphoma).
what is the definition of Sub acute Granulomatous (de Quervain) Thyroiditis?
“tender thyroid”
A self-limited (resolve on its own) disorder in which patients present with a tender thyroid.
what is the etiology of Sub acute Granulomatous (de Quervain) Thyroiditis?
is not known but clinical features of preceding respiratory infection suggest a possible Viral etiology.
gross appearence of Sub acute Granulomatous (de Quervain) Thyroiditis
focal enlargment + moderate asymmetrical growth
- Moderate enlargement of the gland which is often focal and asymmetrical.
- The cut surface of the involved area is firm and yellowish-white.
Microscopic appearence of Sub acute Granulomatous (de Quervain) Thyroiditis
granulomatous shape
- Early, Acute inflammatory destruction of the thyroid follicles.
- Late, Granulomas consist of central colloid material surrounded by histiocytes and scattered multinucleate giant cells.
- advanced cases: Fibrosis.
Etiology of Riedel thyroiditis
“fibrous thyroiditis”
Rare chronic disease of unknown cause, Riedel’s thyroiditis may be part of multifocal idiopathic fibrosclerosis.
Gross appearance of Riedel thyroiditis
The gland is stony hard and adherent to the surrounding structures.
may be mistaken for cancer
Microscopic appearence of Riedel thyroiditis
- Follicles are atrophied
- Excess fibrous tissue may extend outside the gland
- Lymphocytic infiltrate
complications of Riedel thyroiditis
Compression manifestations: dysphagia, dyspnea, recurrent laryngeal nerve paralysis and stridor.
mediastinal syndrome
what is the morphologic appearence of Palpation Thyroiditis?
Morphologically similar appearance to de Quervain thyroiditis
what causes Palpation Thyroiditis?
usually in patients with goiter
May be produced in cases where vigorous thyroid palpation initiate mechanical trauma to the thyroid follicles
what is the definition of goiter?
Non inflammatory, non neoplastic enlargement of the thyroid gland
what are the types of goiter?
- Simple (non toxic)
- Toxic (associated hyperthyroidism)
what is the definition of Simple (non toxic) Goiter?
Enlargement of the thyroid gland without toxic manifestation.
incidence of Simple (non toxic) Goiter
Common in females
what are the causes of Simple (non toxic) Goiter?
1. Absolute iodine deficiency: in area away from seas or due to intake of goitrogenic agents e.g cabbage and cauliflower
2. Relative iodine deficiency: due to increase demand for thyroid hormones as at puberty, pregnancy and lactation
pathogenesis of Simple (non toxic) Goiter
- Deficient thyroid hormones —-> excessive TSH stimulation.
- This leads to hyperplasia of follicular epithelium & formation of new thyroid follicles.
- Diffuse enlargement of the thyroid gland (maintains the euthyroid state).
- Cyclic hyperplastic stage followed by involution stage.
- Involuted nodules undergo fibrosis, calcification, hemorrhage & cystic degeneration.
