Pathology of the thyroid gland - PowerPoint Presentation

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Pathology of the thyroid gland

By :

Shifaa

’

Qa’qa

’

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T

wo bulky lateral lobes

Isthmus

Follicles

Follicular epithelial cells

TSH

Thyroglobulin ---- T4 , T3 ---- bound to circulating plasma proteins

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The interaction of thyroid hormone with its nuclear thyroid hormone receptor (TR) results in the formation of a hormone-receptor complex that binds to

thyroid hormone response elements (TREs) in target genes

, regulating their transcription.

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Hyperthyroidism

Hypothyroidism

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HYPERTHYROIDISM

Thyrotoxicosis

:

Elevated circulating levels of free T3 and T4

Hyperthyroidism is mc

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Manifestations of thyrotoxicosis:

Hypermetabolic

state

heat intolerance

weight loss

despite increased appetite

soft, warm, and flushed skin

malabsorption

, and

diarrhea

Palpitations and tachycardia

congestive heart failure

nervousness,

tremor

, and irritability

50% develop proximal muscle weakness (thyroid myopathy)

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staring gaze and lid lag (

sympathetic overstimulation of the

levator

palpebrae

superioris

)

True thyroid

ophthalmopathy

associated with

proptosis

/

exophthalmus

is a feature seen only in

Graves disease ----

Bilateral, accumulation of

loose

connective tissue, fatty infiltration, mononuclear cells infiltration, and edema

behind the orbits---- corneal damage

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Thyroid storm:

Hyperthyroidism patient ---- stress (

truama

, surgery, emotional, infection,)

---- not receive

Tx

medical emergency

Tachycardia, cardiac arrhythmias (AF), fever, agitation, confusion

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Apathetic hyperthyroidism--- elderly persons

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The measurement of serum TSH is the most useful single screening test for hyperthyroidism

- TSH levels are decreased, increased levels of

free T4 or occasionally free T3

- TSH levels normal or raised ; pituitary- or hypothalamus-associated (secondary) hyperthyroidism

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measurement of radioactive iodine uptake by the thyroid gland often is valuable in determining the etiology

.

such scans may show diffusely increased (whole gland) uptake in Graves disease

increased uptake in a solitary nodule in toxic adenoma

decreased uptake in thyroiditis.

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HYPOTHYROIDISM

Worldwide, the most common cause of hypothyroidism is dietary deficiency of iodine ,

while in most developed nations, autoimmune causes predominate.

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Manifestations:

Cretinism

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Myxedema

:

Gull disease

Generalized apathy

mental sluggishness

cold intolerant

Obese

constipation

coarsening of facial features, enlargement of the tongue, and deepening of the voice (accumulation of

m

ucopolysaccharide

-rich edematous fluid)

heart failure

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measurement of serum TSH is the most sensitive screening test

serum TSH--increased--- primary hypothyroidism

serum TSH—not increased--- secondary

hypothy

Serum T4--- decreased

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THYROIDITIS

inflammation of the thyroid

(1) Hashimoto thyroiditis

(2) granulomatous (de

Quervain

) thyroiditis;

(3)

subacute

lymphocytic thyroiditis

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Hashimoto thyroiditis

:

the mc cause of hypothyroidism in areas of the world where iodine levels are sufficient.

it may be preceded by transient thyrotoxicosis

Chronic Lymphocytic Thyroiditis

45 and 65 years, Females, painless enlargement of the thyroid,

Autoimmune--- other autoimmune diseases

increased risk for the development of B cell non-Hodgkin lymphomas and papillary carcinomas

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antithyroid

antibodies:

antithyroglobulin

,

antithyroid

peroxidase antibodies

The thyroid usually is

diffusely

and

symmetrically

enlarged

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Subacute

Lymphocytic Thyroiditis

:

in a subset of patients the onset of disease follows pregnancy (

postpartum thyroiditis

)

Autoimmune, females

painless neck mass

Thyrotoxicosis ---

euthyroid

--- hypothyroidism

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Subacute

Granulomatous

(de

Quervain

)

Thyroiditis

:

ages of 30 and 50

Females

Viral infection—

hx

of an upper respiratory infection

pain in the neck, fever, malaise

Transient hyperthyroidism--- transient

Hypothyroidism

self-limited

----

euthyroid

state within 6 to 8 weeks.

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Riedel thyroiditis

:

extensive

fibrosis

involving the thyroid and contiguous neck structures

fixed thyroid mass, simulating a thyroid neoplasm.

autoimmune

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GRAVES DISEASE

Graves disease is the most common cause of endogenous hyperthyroidism

Triad of:

1- Thyrotoxicosis (diffusely enlarged thyroid)

2-

Ophthalmopathy

---- exophthalmos

3-

dermopathy

/ pretibial myxedema/ shins (

glycosaminoglycans

and lymphocyte infiltration)

ages of 20 and 40, females, autoimmune

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breakdown in self-tolerance to thyroid

autoantigens

, of which the most important is the

TSH receptor.

Thyroid-stimulating immunoglobulin

Thyroid growth-stimulating

immunoglobulins

TSH-binding inhibitor

immunoglobulins

T cell–mediated-----

ophthalmopathy

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The thyroid gland is enlarged, symmetrically

diffuse

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DIFFUSE AND MULTINODULAR

GOITER

impaired synthesis of thyroid hormone (dietary iodine deficiency)

--------------

compensatory rise in the serum TSH, which in turn causes hypertrophy and hyperplasia of thyroid follicular cells

---------------

Goiter : Enlargement of the thyroid ----- large neck mass---- airway obstruction, dysphagia, and compression of large vessels in the neck and upper thorax

(so-called superior

vena cava syndrome).

---------------------

enough to overcome the hormone deficiency, ensuring a

euthyroid

metabolic state

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Endemic goiter------- little iodine

Sporadic goiter----- physiologic demand for T4, puberty, females

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D

iffuse goiter ---- diffuse, symmetric enlargement of the gland

recurrent episodes of hyperplasia and involution

M

ultinodular

goiter ---- irregular enlargement

of the thyroid

toxic

multinodular

goiter ----- autonomous nodules ----Plummer syndrome