Transcript THYROID - الرئيسية

EMBRYOLOGY
Greek (shield-shaped)
Develops as a thickening in the pharyngeal floor at
the base of the tongue at the foramen cecum that
elongates inferiorly as the thyroglossal duct, dividing
into two lobes as it descends through the neck.
medial anlage(endoderm) give rise to the thyroid
follicular cells –fuse with- lateral anlage
(neuroectoderm) which originate from 4th branchial
pouch give rise to parafollicular (C) cells.
ANATOMY
Largest endocrine gland (20 grams)
Brown and firm
Two lobes , isthmus , pyramidal lobe (50%)
Highly vascularized
Location; anterior in the neck extends from middle of
thyroid cartilage to just above clavicle
C5-T1
2nd-4th tracheal ring(isthmus)
Coverings; skin, platysma, strap muscle (sternothyroid,
sternohyoid, superior belly of omohyoid), deep cervical
fascia(pretracheal fascia), true inner capsule(lobules).
ARTERIAL SUPPLY
-The superior thyroid artery is the first branch of the external carotid artery .
-The inferior thyroid artery branch of the thyrocervical trunk, which comes off the subclavian artery.
-Thyroidea ima arises from aorta (from innominate 1-4 %)
VENOUS DRAINAGE
- The superior and middle thyroid veins drain into the internal jugular veins.
- The inferior thyroid vein drains into the brachiocephalic vein.
LYMPHATIC DRAINAGE
Quite extensive and flows multidirectionally. Immediate drainage flows first to the periglandular nodes, then to
the prelaryngeal (Delphian), pretracheal, and paratracheal nodes along the recurrent laryngeal nerve, and then
to mediastinal lymph nodes.
INNERVATION
- superior, middle, and inferior cervical sympathetic ganglia.
- parasympathetic fibers from the vagus nerves.
NERVES
Recurrent laryngeal N: innervate all the intrinsic muscles of
larynx except the cricothyroid
Left: from vagus , crosses the aortic arch, loops around
ligamentum arteriosum, ascends in the
tracheoesophageal groove.
Right: from vagus , crosses the RT subclavian artery
(more oblique course).
Non-recurrent
LT: rare, in situs inversus.
RT: 1%, associated with vascular anomaly
Superior LN: (external branch) innervate cricothyroid muscle
branch of vagus, travels with STA
HISTOLOGY
Follicle : structural unit of T. gland
Lobule: 20-40 follicles.
Adult thyroid: 3 million follicles
PHYSIOLOGY
IODINE
daily requirement: 0.1 mg
sources: milk, fish, eggs, salt
converted to iodide (deoxidation) in stomach
absorbed in jejunum
stored in thyroid ( >90%)
cleared by (thyroid 30%), (kidneys 70%)
STIMULANTS
- TSH
- EPINEPHRINE
- HUMAN CHORIONIC GONADOTROPHINS
-pregnancy
-gynecologic malignancies
(hydatidiform mole)
-AUTO REGULATION:
-low iodine intake
-iodine excess
T4
T3
THYROID (100%)
THYROID (20%)
LIVER, MUSCLE
KIDNEYS
ANT. PITUITARY
MORE
LESS
LESS
MORE (4 TIMES)
Active form
MORE
LESS
7 DAYS
1 DAY
PRODUCTION
PLASMA LEVEL
POTENCY
TIGHTNESS TO
PLASMA PROTEIN
HALF-LIFE
THYROID HORMONES FUNCTION
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Fetal brain development.
Skeletal maturation.
Increase oxygen consumption, basal metabolic rate
(Na+/K+ ATPase).
Heat production.
Positive inotropic and chronotropic effects on heart
(Ca+ ATPase).
Maintain normal hypoxic and hypercapnic drive in resp. center in the brain.
Increase bone & protein turnover.
Increase the speed of muscle contraction & relaxation.
+ Glycogenolysis, hepatic gluconeogenesis.
+ Intestinal glucose absorption.
+ Cholesterol synthesis & degradation.
THYROID FUNCTION TEST
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TSH : most sensitive & specific test for DX hypo-hyperthyroidism & for optimizing T4 therapy.
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T4 (total)
increase in – hyperthyroidism.
- elevated Tg (pregnancy..).
decrease in
– hypothyroidism.
- decreased Tg (nephrotic S.).
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T3 (total) : important in
– T3 thyrotoxicosis .
(clinical hyperthyroidism with normal T4)
- increased in early hypothyroidism.
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T4 (free)
-early hyperthyroidism ( normal total T4, high free T4).
-Refetoff syndrome ; end organ resistance to T4 (high T4, normal TSH).
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T3 (free)
-important in DX of early hyperthyroidism with normal total T4 &T3 .
THYROID FUNCTION TEST
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THYROTROPIN-RELEASING HORMONE (TRH)
To evaluate pituitary TSH secretory function
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THYROID ANTIBODIES
To diagnose autoimmune thyroiditis (hashimoto , graves)
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SERUM THYROGLOBULIN ( Tg)
Made only by thyroid tissues
Important in DX of:
-thyroiditis, graves, toxic MN goiter.
-detect recurrence of diff. thyroid cancer (most important).
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SERUM CALCITONIN
Sensitive marker of medullary T. cancer.
THYROID IMAGING
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ULTRASOUND
- Non invasive, no radiation
- Solid vs cystic
- Multicentricity
- Assess lymphadenopathy
- Guide FNAB
THYROID IMAGING
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RADIONUCLIDE IMAGING
I 123 : - low dose of radiation
- half-life 12-14 hours
- image lingual thyroid tissues
I 131 :
- higher dose of radiation
- half-life 8-10 days
- screen & treat metastasis of diff. thyroid cancer
“ both demonstrate the size , shape & the functional activity ”
Tc 99m : - short half-life & low dose of radiation
- sensitive for LN metastasis
FDG PET Scan ( F-fluorodeoxyglucose Positron emission Tomography)
- screen for mets when other IXs are negative
- screen for non palbable thyroid lesions
THYROID CT SCAN
THYROID MRI
HYPERTHYROIDISM
HYPOTHYROIDISM
Heat intolerance
Cold intolerance
Wt loss (most common )
Wt gain
Hyper-activity, nervousness, restlessness
Hypo-activity, decreased mobility,
Fatigue
Fatigue
Diarrhea
Constipation
Amenorrhea
Menorrhagia
Warm moist skin
Dry cold thick skin
Hair loss
Brittle hair & nail
Breathlessness, SOB, wheezing, stridor
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Hand tremor
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Staring gaze
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Insomnia
Lethargy, psycho-motor retardation
HYPERTHYROIDISM
HYPOTHYROIDISM
Tachycardia
Bradycardia
Edema
Edema
Normal or high body temperature
Low body temperature
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Coarsening of voice,
Puffy and coarse face
DIFFUSE TOXIC GOITER
(GRAVES DISEASE)
-most common cause of hyperthyroidism 70%
-male : female ( 1:5)
-age 40-60 years
-autoimmune with familial predisposition
-extra-thyroidal pathologies (eye, skin, …)
-treatment :
-anti-thyroid drugs
-radio-active iodine therapy (I131)
-surgical
INDICATIONS OF SURGERY
-confirmed or suspicious of malignancy
-young patients
-pregnant or desire to conceive
-reaction to anti-thyroid drugs
-compressive symptoms
-contraindicated RAI therapy
TYPES OF SURGERY
-total or near total thyroidectomy
for severe cases
-subtotal thyroidectomy (leaving 4-7 gms)
- bilateral subtotal
-total on one side &subtotal on the other side
Hartley dunhill operation
TOXIC MN GOITER
-end stage of non-toxic MNG
-needs several years to occur
-same like GRAVES with no extrathyroidal
manifestations
-treatment is subtotal thyroidectomy
TOXIC ADENOMA (PLUMMERS DISEASE)
-solitary hot nodule with rapid growth
-size usually > 3cm
-younger pts
-rarely malignant
-treatment : lobectomy + isthmusectomy
THYROID STORM
-Hyperthyroidism + fever + agitation or depression
+ cardio-vascular dysfunction
-causes : infection
trauma
surgery
drugs (amiodarone)
Treatment : medical (ICU)
THYROIDITIS
Thyroid is resistant to infection
- extensive blood and lymphatic supply
- high iodine content
- fibrous capsule
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1- Acute (suppurative) thyroiditis
-streptococcus + anaerobes 70%
-more common in children
-symptoms
-severe neck pain
-fever, chills
-odynophagia
-dysphonia
-DX : leukocytosis
FNAB ; gram stain, culture, cytology
-treatment : IV antibiotic + drainage of abscess
2- Subacute thyroiditis
-painful, painless
-unknown etiology..viral, autoimmune
-stages
-initial hyperthyroid phase
-euthyroid phase
-hypothyroid phase 25%
-resolution phase > 90%
-treatment - medical
- thyroidectomy (rare)
-no response to medical RX
-recurrent
3-Chronic lymphocytic (hashimoto) thyroiditis
-most common inflammatory thyroid disorder
-leading cause of hypothyroidism
-autoimmune, inherited
-male : female ( 1:15)
-age 30-50 year
-presentation
–mild, diffuse & firm thyroid enlargement
-painless
-hypothyroidism 20%
-hyperthyroidism 5%
-treatment
-medical
-thyroidectomy(rare) indicated if
-suspicious for malignancy
-compressive symptoms
-cosmetic
4- Riedels thyroiditis
-invasive fibrous thyroiditis
-replacement of thyroid T by fibrous T
-rare
-autoimmune
-more in females
-age 30-60 year
-presentation
-hard ant. neck mass (fixed)
-compressive symptoms
-hypothyroidism
-hypoparathyroidism
-DX : open BX
-treatment
-medical
-surgical -wedge resection of isthmus to decompress the trachea
GOITER
(ANY ENLARGMENT OF THYROID GLAND)
DIFFUSE, UNINODULAR, MULTINODULAR
TOXIC, NON-TOXIC
CAUSES
-ENDEMIC : low iodine intake
-MEDICATIONS: iodide, amiodarone, lithium
-THYROIDITIS : sub-acute, chronic
-FAMILIAL : enzyme defect
-NEOPLASM : adenoma, carcinoma
-GOITROGENS : kelp, cassava, cabbage
INDICATIONS OF SURGERY IN SIMPLE GOITER
-obstructive symptoms
-substernal extention
-suspicious of malignancy
-increase in size despite T4 suppresion
-cosmetic
“ subtotal thyroidectomy”
SOLITARY THYROID NODULE
FNAB
1*NON DIAGNOSTIC … repeat
2*MALIGNANT…thyroidectomy
3*SUSPICIOUS(FOLLICULAR)
=RAI scan
-cold… thyroidectomy
-hot … RAI / thyroidectomy
4*BENIGHN
-Cyst.. Aspirate.. Reaccumulates#3
thyroidectomy
-Colloid nodule.. Observe.. Continued
growth or compressive symptom
thyroidectomy
THYROID CYST
-Resolve with aspiration 75%
-indication of thyroidectomy
-failure to do complete aspiration
- > 4cm
-complex (solid-cystic).. 15% malig.
-recurrence after 3 aspiration
THYROID CANCER
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1% of all cancers.
Male : female ( 1: 4 ).
The usual presentation is neck swelling.
Well differentiated to anaplastic.
Curable to very poor prognosis.
Surgical treatment is controversial.
PAPILLARY CARCINOMA
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80%.
Male : female (1 : 2).
Mean age (30-40 years).
> in children.
> in individuals who exposed to external radiation.
Presentation –euthyroid
- neck mass ( painless )
-dysphagia, dyspnea, dysphonia
( localy invasive )
US to evaluate the contra lateral lobe & L-Nodes.
Multifocality 85%.
L-Nodes metastasis is common.
Distant mets ( uncommon) at time of DX but with time might reach up to 20 % …. Lung is
the most common site then bone, liver & brain.
Prognosis: 10-year survival > 95%
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Histology ( 3 variants):
-pure papillary
-mixed ( papillary + follicular)
-follicular variant of papillary
“ All behave biologically as papillary ca “
-other rare variant (1%) with worse prognosis;
tall cell,insular,columnar,clear cell,trabicular,diffuse
sclerosing, poorly diff.
Occult or minimal micro carcinoma
-incidental or autopsy findings
-< 1 cm
-no thyroid capsule invasion
-no angioinvasion
-no LN or distant mets
“ best prognosis “
Prognosis
1.
AGES scoring system
Low risk
High risk
Age
Young < 40
Old >40
Histological grade
Well diff.
Poorly diff.
Extra thyroidal
invasion
No
Yes
Tumor size
(1ry lesion)
Small size < 5cm
Large > 5cm
Distant metastasis
No
Yes
Prognosis
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3.
4.
5.
DeGroot scale
class 1 : intrathyroidal
class 2 : cervical LN mets
class 3 : extrathyroidal invasion
class 4 : distant metastasis
MACIS scale
AMES scale
TNM
TREATMENT
SURGICAL TREATMENT
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OCCULT/MINIMAL PAPILLARY CA
LOBECTOMY
ALL OTHER PAPILLARY CA
TOTAL OR NEAR TOTAL THYROIDECTOMY
BOTH WITH
CENTRAL LYMPHADENECTOMY
Advantages of total thyroidectomy
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Enables the use of RAI to detect and treat residual tissue & mets.
Makes serum Tg more sensitive to detect recurrence.
Eliminate contra lateral occult ca (85% of papillary ca are bilateral).
Decreases the 1% risk of progression to undiff. Or anaplastic variants.
Reduces the need for 2nd surgery.
Complication rate < 2%.
Improves survival.
Advantages of hemithyroidectomy
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2.
3.
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5.
Less complication rate than total.
Recurrence in remaining lobe is unusual (<5%).
Most of recurrences are curable by surgery.
Total & hemithyroidectomy almost have the same prognosis.
Multicentricity usually has little prognostic significance .
FOLLICULAR CARCINOMA
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10%.
Male : female (1 : 3).
Mean age (50years).
More common in iodine deficient area so iodine supplementation decrease the incidence.
Presentation –euthyroid,
- hyperthyroidism (<1%)
- solitary neck mass ( painless )
- sometimes rapid increase in size
- pain due to hemorrhage (uncommon)
L-Nodes metastasis is uncommon ( 5%).
Distant mets > papillary ( venous spread).
FNAB is unable to diff. benign from malignant.
Goes with malignancy
–older age
-large tumors > 4cm
-distant mets
Usually solitary capsulated lesion.
Capsular & vascular invasions are common.
SURGICAL TREATMENT
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FNAB : if follicular neoplasm do
lobectomy.
( 80% adenoma )
If tumor size > 4 cm in older patients do
total thyroidectomy.
(risk of malignancy 50%)
If there is local invasion, capsular invasion, vascular invasion,
LN involvement do
-total thyroidectomy (frozen section)
-completion thyroidectomy (formal BX)
MORTALITY
 10-Year survival : 85%
 20-Year survival : 70%
POOR PROGNOSIS
 Age > 50 year
 Tumor size >4cm
 High tumor grade
 Marked vascular invasion
 Extra thyroidal invasion
 Distant mets
HURTHLE CELL TUMORS
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3%
Subtype of follicular T. cancer
Can not be diagnosed by FNAB
Characterized by vascular & capsular invasion
Contains sheets of eosinophilic cells packed with
mitochondria
Differ from follicular by :
-multifocal & bilateral (30%)
-do not take RAI
-metastasize to LN (25%)
-less 10-year survival (80%)
HURTHLE CELL TUMORS TREATMENT
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ADENOMA: lobectomy
INVASIVE CA : total thyroidectomy + central
cervical LN removal
MEDULLARTY CARCINOMA
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5%
Male : female (1: 1.5)
Age 50-60 years
C cells tumor, concentrated in superolateral part of thyroid lobes
Presentation –neck mass
-pain (common)
-palpable cervical LN (20%)
-dysphagia, dyspnea, dysphonia
-diarrhea due to increase int. motility
-cushing syndrome (4%) due to ectopic production
of ACTH
Distant blood borne mets.. Liver, bone , lung
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Types
-Sporadic (75%)
older age, unilateral (80%)
-Familial (25%) Familial MTC, MEN2A, MEN2B
younger age, bilateral (90%)
Secrete Calcitonin, CEA, Serotonin, prostaglandin E2
& F2a, ACTH
TREATMENT
TOTAL THYROIDECTOMY WITH BILATERAL
CENTRAL CERVICAL LN DISSECTION
10-year survival : 35-80 %
ANAPLASTIC CARCINOMA
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1%
Female > male
Age 70-80 year
Presentation
–long standing large mass
-rapid enlargement & pain
-might be fixed & ulcerated
-palpable LN
- dysphagia, dyspnea, dysphonia
TREATMENT
*ISTHMUSECTOMY w/o TRACHEOSTOMY
to release tracheal obstruction
*THYROIDECTOMY
for resectable tumors will add nothing to survival
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Very aggressive tumor, most patients die within 6
months of DX
LYMPHOMA
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< 1%
Non-Hodgkins B-cell type
Usually isolated but might be a part of generalized
disease
Usually comes on top of chronic lymphocytic
thyroiditis
Presentation
–painless rapidly enlarging mass
-respiratory distress
TREATMENT
Respond well to
-chemotherapy
-combined therapy (chemo- radiotherapy)
-thyroidectomy + LN resection used only to
release airway obstruction
Prognosis : 5-year survival ( 50%)
METASTATIC CARCINOMA
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Thyroid is a rare site for metastasis.
Usually from kidneys, breast, lungs, melanoma.
Thyroidectomy might be helpful if the 1ry is
controlable,
COMPLICATIONS OF THYROID SURGERY
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RLN injury
- < 1%
- RT > LT
- treatment : 1ry reapproximation
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SLN injury (external branch)
Cervical sympathetic trunk injury ( Horners syndrome)
- in extensive surgery
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Parathyroid glands injury
- transient hypocalcaemia 50%
- permanent hypothyroidism < 2%
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Carotid artery, jugular vein and esophagus injuries
infrequent
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Hematoma
Seroma
Wound infection
NERVE INJURY
Unilateral RLN
ipsilateral vocal cord paralysis
- paramedian position; normal but weak voice.
- abducted position; hoarse voice, ineffective cough.
Bilateral RLN
Bilateral VC paralysis
- paramedian position; airway obstruction, voice loss.
(?? Tracheostomy)
- abducted position; ineffective cough, aspiration, resp. tract inf.
Superior LN
Inability to tense ipsilateral VC
abnormal voice (high notes), voice fatigue.
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