- thyroid descends along a pathway which creates a virtual (or actual) duct known as the thyroglossal duct - ectopic or otherwise pathologic thyroid may be seen anywhere along this pathway in adult life

ECTOPIC THYROID - mass in foramen cecum of tongue, most commonly in women - dysphagia, dyspnea, dysphonia - rare, most common location of functioning ectopic thyroid - 70% associated with absence of cervical thyroid

ECTOPIC THYROID - often thyroid tissue that has dropped into anterior mediastinum, seen with cervical goiter - may be symptomatic (dyspnea, dysphagia, hyperthyroid, hypothyroid) or not

ECTOPIC THYROID - NOT a product of misplaced ovarian tissue during organogenesis - monodermal teratoma of ovary, composed mainly (50%) of adult thyroid tissue - may functionally cause thyrotoxicosis - adenomas are common, 5% malignant

- diffuse hyperplasia associated with Graves disease (85% of hyperthyroidism) - thyroiditis (early in course) - exogenous thyroid hormone administration - hyperfunctional multinodular goiter - hyperfunctional thyroid adenoma

- ocular changes due to sympathetic overstimulation of the levator palpebrae superioris and to accumulation of loose connective tissue behind the eyes - Exopthalmos - Fatigue, weight loss, increased appetite - Tachycardia - Muscular weakness

- Thyroiditis - Radiation (radioactive iodine, external radiation) - Surgical excision of thyroid - Developmental anomaly (Cretinism) - Interference with thyroid hormone synthesis (I deficiency, lithium) - Suprathyroidal (pituitary/hypothalamic lesions)

Pathology-Handorf Flashcards by Katie Thurman

Glandular

“acorn”
-an aggregation of cells, specialized to secrete or excrete materials not related to their ordinary metabolic needs
Contrast: tissue, organ, system, compartment
Define: autocrine, paracrine, endocrine

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Paracrine

adjacent target cell

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Autocrine

targets sites on same cells

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Endocrine

distant target cell using blood vessel

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Thyroid Development

thyroid descends along a pathway which creates a virtual (or actual) duct known as the thyroglossal duct
ectopic or otherwise pathologic thyroid may be seen anywhere along this pathway in adult life

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Lingual Thyroid

ECTOPIC THYROID

mass in foramen cecum of tongue, most commonly in women
dysphagia, dyspnea, dysphonia
rare, most common location of functioning ectopic thyroid
70% associated with absence of cervical thyroid

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Thyroglossal Duct Cyst

ECTOPIC THYROID

usually midline, between isthmus of thyroid and hyoid bone
usually apparent at birth or in childhood
tend to have repeated infection
not hormonally active

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Substernal Goiter

ECTOPIC THYROID

often thyroid tissue that has dropped into anterior mediastinum, seen with cervical goiter
may be symptomatic (dyspnea, dysphagia, hyperthyroid, hypothyroid) or not

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Lateral Aberrant Thyroid

ECTOPIC THYROID

aberrant thyroid/embryonic rests in lateral neck, sometimes in lymph nodes
in adults most likely metastatic follicular thyroid carcinoma

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Suprahyoid/Infrahyoid Thyroid

ECTOPIC THYROID

similar location to thyroglossal duct cyst
often hypothyroid (absent cervical thyroid)

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Struma Cordis

ECTOPIC THYROID

-ectopic thyroid tissue in heart, usually right ventricle

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Struma Ovarii

ECTOPIC THYROID

NOT a product of misplaced ovarian tissue during organogenesis
monodermal teratoma of ovary, composed mainly (50%) of adult thyroid tissue
may functionally cause thyrotoxicosis
adenomas are common, 5% malignant

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Hyperthyroidism

diffuse hyperplasia associated with Graves disease (85% of hyperthyroidism)
thyroiditis (early in course)
exogenous thyroid hormone administration
hyperfunctional multinodular goiter
hyperfunctional thyroid adenoma

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Graves Disease

ocular changes due to sympathetic overstimulation of the levator palpebrae superioris and to accumulation of loose connective tissue behind the eyes
Exopthalmos
Fatigue, weight loss, increased appetite
Tachycardia
Muscular weakness

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Pathophysiology of Graves Disease

-immune mediated production of TSH receptor antibodies:
binding of abs to thyroid TSH receptors causes thyroid stimulation without negative feedback
-binding of same abs to other tissue sites causes increased production of glycosamingclycans with resultant tissue effects (exopathalmos/myxedema)

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Histopathology of Graves Disease

thyroid epithelium is hyperplastic “too many cells”
heaped up folds of hyperplastic epithelium are present
“scalloped” colloid with bubbles, from rapid colloid turnover

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Hypothyroidism?

Thyroiditis
Radiation (radioactive iodine, external radiation)
Surgical excision of thyroid
Developmental anomaly (Cretinism)
Interference with thyroid hormone synthesis (I deficiency, lithium)
Suprathyroidal (pituitary/hypothalamic lesions)

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Types of Thyroditis

1) Hashimoto Thyroiditis (Chronis Autoimmune thyroiditis)
2) Subacute (granulomatous)
3) Subacute Lymphocytic (painless)
4) Riedel Thyroiditis
5) Infectious Thyroiditis

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Hashimoto Thyroiditis

-commonest cause of hypothyroidism in North America, where dietary iodine is sufficient
-autoimmune etiology; T cell defect
-10-20X more women
Hyper-early
Hypo-late
-intense lymphocytic infiltration with tissue destruction and early fibrosis

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Subacute (Granulomatous) Thyroiditis

“DeQuervain thyroiditis”

3-5X more women
peak in summer

Subacute Lymphocytic (painless) Thyroiditis

-without granulomas or giant cells

Riedel Thyroiditis

unusual disorder of unknown cause
characterized by fibrosis of thyroid and other neck structures
fibrosis in distant sites (retroperitoneum) may be seen
collagen

Infectious Thyroiditis

The thyroid is not immune from infection by a variety of systemic agents
B/C its highly vascularized (1/4 blood supply)

Diffuse and Multinodular Goiter

diffuse/nontoxic/simple/colloid goiter
- endemic goiter
- sporadic
multinodular goiter
best thought of as a spectrum of diseases with considerable overlap, caused by a # of different etiologies

Goiter

-chronic enlargement of thyroid gland, not due to neoplasm, occurring endemically in certain locations, especially regions where glaciation occurred and the soil is low in iodine, and sporadically elsewhere

Endemic Goiter

- occurs in areas where environment is low in naturally occurring iodine - "endemic" if more than 10% of population has goiter - diet, genetics play a role - starts as diffuse thyroid enlargement, but generally progress (through multiple episodes of regression and enlargement) to multinodular state

Function of Pituitary Gland?

-critical role in regulation of most other endocrine glands

Anterior pituitary?

- more vascularized | - releases GH, PRL, ACTH, FSH, LH, TSH

Posterior pituitary?

- less vascularized | - Oxytocin, ADH

Most cells of the pituitary gland secrete?

GH 40-50% | Prolactin 20-25%

Micrograph of Anterior Pituitary

- vasculature is red | - some cells are in clusters

Development of Pituitary?

- adenohypophysis - neurohypophysis - vascular supply

Hypopituitarism

- postsurgical - postirradiation - cysts - tumors - ischemia/hemorrhage - inflammation - empty sella syndrome - gene defect

Most common cause of Hypopituitarism?

TUMOR - Benign Adenomas

Infarction of Pituitary

- usually involves anterior lobe due to vascular supply | - about 75% of lobe must be lost for symptoms to occur (more endocrine function than we need)

Causes of Pituitary Infarction?

- Diabetes Mellitus - Intracranial Pressure - CVA - Hypoperfusion of any cause - Sheehan's Syndrome - Pituitary Apoplexy

Sheehan's Syndrome

- in postpartum women, infarct of pituitary due to massive blood loss - presents >1 month after birth - lack of prolactin/no milk/no periods

Inflammatory Lesions of Pituitary

- acute inflammation (sinusitis, osteomyelitis) - granulomatous (TB, fungal, sarcoid, idiopathic giant cell granuloma) - Lymphocytic (autoimmune)

Non-Infections Granulomas of CNS are located where most?

-skull/base (pituitary/cranial nerves)

Hyperpituitarism

- hyperplasia (big gland, uncommon) - pituitary adenoma (most common) - ectopic secretion by non-pituitary tumor - hypothalmic disorder

Pituitary Hyperplasia

- uncommon - primary vs secondary - nodular or diffuse pattern of gland involvement - increase in cell number - ex: ACTH hyperplasia in Addison's disease

Pituitary Adenomas

-10% of intercranial neoplasms -30-50 year olds -usually isolated (can be part of MEN syndrome) -functional tumors detected eariler -slow growing Common Symptoms: headache, compression of optic chasm

Pituitary Carcinoma

- very rare - middle age - isolated, sporatic

Types of Pituitary Adenomas

1/2 are prolactin | 1/4 are GH producing

Gross Morphology of Pituitary Adenoma

- typically fragmented due to standard transsphenoidal surgical approach - well circumscribed - macro vs microadenoma (1cm cut-off) - larger lesions may extend into suprasellar region

Histopathology of Pituitary Adenoma

- sheet-like growth pattern - relative cellular monomorphism - loss of typical reticulin fiber network - functional status cannot be predicted from routine histologic appearance - immunohistochemical stains can be confirmatory

Microscopic Pituitary Adenoma

- hypercellular - less vascular - bigger nuclei - no clustering - no mitotic figures

Diabetes Insipidus

- ADH deficiency - excretion of large volume of dilute urine - hypernatremia and increased osmolality - spontaneous or as a result of various conditions including trauma, tumors, inflammatory disorders, or post surgical

SIADH

- ADH excess - usually caused by ectopic secretion by tumor (small cell lung cancer) - hyponatremia, cerebral edema, neurologic dysfunction