5.Thyroid Gland Lecture

7/31/2019 5.Thyroid Gland Lecture

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Dr Sajad Ahmad Salati

MBBS MS MRCS (Glasgow)

Thyroid gland


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Brownish-red, highly vascular gland

Location: ant neck at C5-T1, overlays 2nd 4thtracheal rings

Average width: 12-15 mm (each lobe)

Average height: 50-60 mm long

Average weight: 25-30 g in adults (slightly morein women)

**enlarges during menstruation and pregnancy**


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Under middle layer of deep cervical fascia (pre-tracheal)

thyroid inner true capsule thin and closely adherentto the gland capsule extensions within the gland form septae, dividing

it into lobes and lobules lobules are composed of follicles = structural units of the

gland epithelium layer enclosing a colloid-filled cavity

colloid (pink on H&E stain) contains an iodinatedglycoprotein, iodo-thyroglobulin (precursor of thyroidhormones).


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Epithelial cells = 2 types:

( follicular) formation ofcolloid (iodothyroglobulin)

( C cells -clear, light),lie adjacent to follicles w/in basallamina produce calcitonin


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Superior Laryngeal has two branches1. External -innervates cricothyroid and inf. constrictor of pharynx.2. Internal -sensory innervation ABOVE vocal folds

Recurrent Laryngeal innervates ALL muscles of Larynx EXCEPTcricothyroid.

The left and right have a different path!-Left recurrent laryngeal loops around the arch of AORTA -its foundin Sup. Mediastinum and neck.

-Right recurrent laryngeal loops around right SUBCLAVIAN A. so itsfound only in the neck.

Lesions of Superior Laryngeal Nerve are mostly asymptomatic,because its fibers are mainly sensory. If the motor fibers to thecricothyroid are affected in the external branch, there may be some

mild hoarseness and a slight decrease in vocal strength.

Both recurrent laryngeal nerves are susceptible to injury in surgicalprocedures involving the thyroid. Lesions result in a fixed vocal cordand transient hoarseness.*Left recurrent is injured more frequently than right.


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: superior and inferior thyroid arteries (occasional

thyroidea ima)

collateral anastomoses (ipsi and contralaterally)

thyroid ima (when present) originates from aorticarch or innominate artery, enters the thyroid atinferior border of isthmus.


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first anterior branch ECA

descends laterally to thelarynx under the omohyoidand sternohyoid muscles

runs superficially on theanterior border of the laterallobe, sending a branch deepinto the gland before curvingtoward the isthmus where itanastomoses with thecontralateral artery
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Relationship with SLN:

Cephalad to the superior pole, ext branchof SLN runs w/ STA before turningmedially supply cricothyroid muscle

**careful when ligating artery**


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SCA thyrocervical trunk ITA

ITA ascends vertically andthen curves medially to enterthe tracheoesophagealgroove (posterior to carotidsheath)

Branches penetrate the

posterior aspect of the laterallobe


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Relationship with RLN: RLN ascends in the TE groove

and enters the larynx b/w theinferior cornu of the thyroidcartilage and the arch of the

cricoid RLN can be found after it

emerges from the superiorthoracic outlet:

Sup: thyroid lobe

Lat: common carotid artery

Medial: trachea


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3 pairs of veins: asc along STA and

becomes a tributary of the IJV

directly lateral

IJV(variable): R passes ant to

innominate a R BCV orant trachea L BCV

L drainage L BCV

**occ both inf veins form acommon trunk thyroid imavein empties into L BCV


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Extensive, multidirectional flow periglandular prelaryngeal (Delphian) pretracheal paratracheal (along RLN) brachiocephalic (sup mediastinum)

deep cervical thoracic duct

NB: regional metastasis of thyroidcarcinoma are superior and lateral, alongIJV ie: invasion of the pretracheal andparatracheal LNs and obstruction ofnormal lymph flow.


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Follicular cells Produce , store and releasethryroxine (T4 ) and tri-iodothyronine (T 3 ) major regulators of basal metabolism.

Para follicular cells ( C cells) secretecalcitonin a harmone with minor role incalcium homeostasis.


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Serum thyroid hormone levels (TSH, and if TSH is abnormal than T3,T4 levels)

Euthyroid Normal Normal Normal

Thyrotoxic Undetectable High High

Myxoedema High Low Low


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Serum levels of antibodies against thyroid peroxidase (TPO)& thyroglobulin

These are useful in determining the cause of thyroid

dysfunction and swellings.


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Simple radiographs of the chest and thoracic inlet will rapidlyand economically confirm the presence of significantretrosternal goitre and clinically important degrees oftracheal deviation and compression.

Pulmonary metastases may also be detected


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High-frequency ultrasound scanninggives good anatomical images of thethyroid and surrounding structures

Aids in aspiration cytology


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The uptake by the thyroid of a low dose of either radiolabelled

iodine (123I) or the cheaper technetium (99mTc) will demonstrate

the distribution of activity in the whole gland. Routine isotope

scanning is unnecessary and inappropriate for distinguishing

benign from malignant lesions because the majority (80%) of cold

swellings are benign and some (5%) functioning or warm swellings

will be malignant. Its principal value is in the toxic patient with a

nodule or nodularity of the thyroid.

Technetium thyroid scan showing acold nodule that does not take up

isotope expanding the left thyroid

lobe.


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Whole-body scanning is used to demonstrate metastases butthe patient must have all normally functioning thyroid

tissue ablated, either by surgery or radioiodine, before thescan is performed, because thyroid cancer cannot competewith normal thyroid tissue in the uptake of iodine.


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Fine-needle aspiration cytology (FNAC) is the investigation ofchoice for discrete thyroid swellings. FNAC has excellentpatient compliance, is simple and quick to perform in the out-patient department and is readily repeated.


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Non-goitrous: primary myxoedema

Goitrous: Hashimotos disease

After thyroidectomy

After radioiodine therapy

Drug induced (anti-thyroid drugs, para-aminosalicylic acid and

iodides in excess)

Often goitrous and due to iodine deficiency


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Consequence of inadequate thyroid hormone production

during fetal and neonatal development.Sporadic or endemic

A hoarse cry, macroglossia and umbilical hernia in aneonate with features of thyroid failure suggests thediagnosis. Immediate diagnosis and treatment withthyroxine within a few days of birth are essential


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The symptoms are:

tiredness;

mental lethargy;

cold intolerance;

weight gain;

constipation;

menstrual disturbance;

carpal tunnel

syndrome

The signs of thyroid deficiency

are:

bradycardia;

cold extremities;

dry skin and hair;

periorbital puffiness;

hoarse voice;

bradykinesis, slow movements;

delayed relaxation phase ofankle jerks.

.


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These show low T4 and T3 levels with a high TSH

(except in the rare event of pituitary failure) .Highserum levels of TPO antibodies are characteristic ofautoimmune disease.

Replacement of thyroxine ( T3 in some cases)


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The normal thyroid gland is impalpable. The term goitre (Latin guttur= the throat) is used to describe generalised enlargement of thethyroid gland.

A discrete swelling (nodule) in one lobe with no palpable abnormalityelsewhere is termed an isolated (or solitary) swelling.


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Diffuse hyperplastic

Physiological

Pubertal

Pregnancy

Multinodular goitre

Diffuse

Graves disease

Multinodular

Toxic adenoma

Benign

Malignant

Autoimmune

Chronic lymphocyticthyroiditis

Hashimotos disease

Granulomatous

De Quervains thyroiditisFibrosing

Riedels thyroiditis

Infective

Acute (bacterial thyroiditis,viral thyroiditis, subacute

thyroiditis) Chronic (tuberculous,

syphilitic)

Other e.g., Amyloid


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Simple goiter generally develops as a result of stimulationof the thyroid gland by TSH,

in response to a chronically low level of circulatingthyroid hormones (common).

or as a result of inappropriate secretion from a micro-adenoma in the anterior pituitary (which is rare)

The most important factor in endemic goiter is dietarydeficiency of iodine, but defective hormone synthesisprobably accounts for many sporadic goiters .


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The stages in goitre formation are as follows:

Persistent growth stimulation causes diffuse hyperplasia; all lobules are

composed of active follicles and iodine uptake is uniform. This is a, which may persist for a long time but isreversible if stimulation ceases.

Later, as a result of fluctuating stimulation, a mixed pattern developswith areas of active lobules and areas of inactive lobules.

Active lobules become more vascular and hyperplastic until haemorrhageoccurs, causing central necrosis and leaving only a surrounding rind ofactive follicles.

Necrotic lobules coalesce to form nodules filled with either iodine-free

colloid or a mass of new but inactive follicles. Continual repetition of this process results in a . Most

nodules are inactive, and active follicles are present only in theinternodular tissue


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Diffuse hyperplasia corresponds to the first stages of the natural history. Thegoitre appears in childhood in endemic areas but, in sporadic cases, itusually occurs at puberty when metabolic demands are high. If TSHstimulation ceases the goitre may regress; however, it tends to recur later attimes of stress such as pregnancy.

The goitre is soft, diffuse and may become large enough to cause discomfort. Awhen TSH stimulation has

fallen off and when many follicles are inactive and full of colloid


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This is the later stage of simple goiter development;sometimes only a single nodule is visible but properevaluation reveals multinodularity.

Diagnosis is usually straightforward. The patient iseuthyroid, the nodules are palpable and often visible

(smooth, usually firm and not hard) and the goiter ispainless and moves freely on swallowing.


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may occur because of gross lateral displacementor compression in a lateral or anteroposterior plane by retrosternal extension of

the goiter .

may follow hemorrhage into a noduleimpacted in the thoracic inlet.

Transient episodes of mild hyperthyroidism are common, occurringin up to 30% of patients.

An increased incidence of cancer (usually follicular) has been reported fromendemic areas. Dominant or rapidly growing nodules in longstanding goitersshould always be subjected to aspiration cytology.


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Medical : Prevention in endemic areas by iodization of salt.Replacement of thyroxine

Indications for surgery

Cosmetic

Pressure symptoms Anxiety of patient

Choice Total / subtotal thyroidectomy withsuppressive doses of thyroxine.


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Discrete thyroid swellings (thyroid nodules) arecommon and are present in about 4% of the adultpopulation. They are three to four times morefrequent in women than men.

A discrete swelling inan otherwise impalpable gland is termed isolatedor solitary:

Discrete swelling in a gland withclinical evidence of generalised abnormality in theform of a palpable contralateral lobe or generalisedmild nodularity .


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About 70% of discrete thyroid swellings areclinically isolated and about 30% are

dominant. The importance of discrete swellings lies in

the increased risk of neoplasia comparedwith other thyroid swellings. Some 15% ofisolated swellings prove to be malignant,and an additional 3040% are follicularadenomas. The remainder are non-neoplastic, largely consisting of areas ofcolloid degeneration, thyroiditis or cysts.


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Thorough and .

In males , the index of suspicion for malignancy should be

high even though nodules are commoner in females. Factors to be assessed include:

Duration of the nodule

Symptoms of toxicity

Local symptoms like pressure, pain , dysphagia or

hoarseness

Family history

Exposure to radiation

Physical examination include

careful palpation of remainder of gland and cervical lymphnodes.

Thoracic outlet obstruction needs to be ruled out(Pembertons test).

Indirect laryngoscopy


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: In patients who have history of radiation exposure (which also causes parathyroid adenoma) or family history of MENsyndrome. Patients with family history of MEN -2 syndrome shouldhave analysis to rule out pheochromocytoma( like urinarycatecholamines).

: Single most important study ; thisstudy decreases unnecessary surgical interventions ;

because the distinction is made by architecturalcharacteristics like capsular and vascular invasion which are notdetectable by cytology.

: Used to supplement physical exam to determine whether thenodule is cystic or solid , or whether additional nodules/lymphnodes exist or the size of nodule.


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Routine FNAC (or ultrasonography) shows that over 30% of clinically isolatedswellings contain fluid and are cystic or partly cystic.

Tense cysts may be hard and mimic carcinoma.

Bleeding into a cyst often presents with a history of sudden painful swelling,which resolves to a variable extent over a period of weeks if untreated.

About 50% of cystic swellings are the result of colloid degeneration or are of

uncertain aetiology. Although most of the remainder are the result ofinvolution in follicular adenomas

10-15 % cysts can be malignant.


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Hyperthyroidism is the syndrome caused by excessive secretion ofthyroid hormones. Causes include-

diffuse toxic goitre (Graves disease) commonest cause ;

toxic nodular goitre;

toxic nodule;

hyperthyroidism due to rarer causes.


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NervousnessRestlessnessEmotional labilityFast speechFine tremor

TachycardiaPalpitationsArrhythmiasDyspnea

Lid lagExophthalmosIncreased sweatingFatigueWeaknessHair lossLeg swellingPretibial myxedema


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Graves disease, a diffuse vascular goitre appearing at thesame time as the features of hyperthyroidism, usuallyoccurs in younger women .It is frequently associated witheye signs and pretibial myxedema. The syndrome is that ofprimary thyrotoxicosis ;50% of patients have a familyhistory of autoimmune endocrine diseases. The whole ofthe functioning thyroid tissue is involved, and thehypertrophy and hyperplasia are due to abnormal thyroid-

stimulating antibodies (TSH-RAbs) that bind to TSHreceptor sites and produce a disproportionate andprolonged effect. The pathogenesis of pretibial myxedemaand exophthalmos is not well understood.


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Three possible modes of treatment :1. Medical blockade of the harmone and its

effects

2. Radio iodine ablation of active thyroidtissue

3. Surgical resection of thyroid gland.


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Iodide : ( potassium iodide or as Lugols solution Pot.iodide+ 5% iodine) : Inhibits the release of thyroid hormones fromthe gland .

Effect is short lived ( 1-2 weeks).

Beta blockers like propranolol : Decrease the peripheralconversion of T4 to T3.

Thionamides ( propylthiouracil, methimazole) : Interfere withsynthesis of thyroid harmones and reduces peripheralconversion of T4 to T3. About 1/3rd of patients who toleratethionamides remain in remission after 1 year of treatment ,the other 2/3rd require other modes of treatment. 5-10% ofpatients have adverse reactions to drugs which includecholestasis, arthalgias, headache, neuritis, dependent edema

and reversible granulocytopenia.

Advantages. No surgery and no use of radioactive materials.

Disadvantages. Treatment is prolonged and the failure rateis atleast 50%.


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131

I in a dose of 80 microCurie/gram of estimated thyroid tissue isadministered. The radioactive iodine is taken up by thyroid cells andget destroyed.

Effective in most patients though some may require second or eventhird dose if the pt has symptoms after 6 mths of treatment. Over50% - 70% become hypothyroid with 5-10 yrs.

Safe

Advantages. No surgery and no prolonged drug therapy.

Disadvantages. Isotope facilities must be available.


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Surgical excision of thyroid (total/subtotal thyroidectomy)Advantages. The goitre is removed, the cure is rapid and the

cure rate is high if surgery has been adequate.

Disadvantages. Recurrence of thyrotoxicosis occurs inapproximately5% of cases if less than total thyroidectomy is

carried out. There is a risk of permanent hypoparathyroidismand nerve injury. Young women tend to have a worsecosmetic result from the scar


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In patients over 45 years(earlier if familiesare complete) , radioiodine is appropriate.

In those under 45 years, surgery for thelarge goitre and anti-thyroid drugs or

radioiodine for the small goitre isrecommended.


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A simple nodular goitre is present for a long time before the

hyperthyroidism, usually in the middle-aged or elderly, and is very

infrequently associated with eye signs. The syndrome is that of

secondary thyrotoxicosis.

In many cases of toxic nodular goitre the nodules are inactive

and it is the internodular thyroid tissue that is overactive.

However, in some toxic nodular goitres, one or more nodules are

overactive and here the hyperthyroidism is due to autonomous

thyroid tissue as in a toxic adenoma.

Toxic nodular goitre is often large and uncomfortable and enlarges

still further with anti-thyroid drugs. Large goitres should be

treated surgically because they do not respond as well or as rapidly

to radioiodine or anti-thyroid drugs as a diffuse toxic goitre.


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A toxic nodule is a solitary overactive nodule, which may be partof a generalised nodularity or a true toxic adenoma. It is

autonomous and its hypertrophy and hyperplasia are not due to

TSH-RAb. TSH secretion is suppressed by the high level ofcirculating

thyroid hormones and the normal thyroid tissue surrounding

the nodule is itself suppressed and inactive.

Surgery or radioiodine treatment is appropriate. Resection iseasy, certain and without morbidity. Radioiodine is a goodalternative for those over the age of 45 years because thesuppressed thyroid tissue does not take up iodine and thereis thus no risk of delayed thyroid insufficiency


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In general, radioiodine is the treatment of choice,but antithyroid drugs may be used in young womenintending to have children. Further surgery has

little place.

In this case, surgery or thyroid ablation with 123I isappropriate.


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Radioiodine is absolutely contraindicated in pregnancy because

of the risk to the fetus. The danger of surgery is miscarriage and

the danger of anti-thyroid drugs is of inducing thyroidinsufficiency

in the mother and, because both TSH and anti-thyroid

drugs cross the placenta, of the baby being born goitrous andhypothyroid. The risk of either surgery in the second

trimester, in competent hands is very small and isrecommended.

Radioiodine is contraindicated because of the theoretical risk of

inducing thyroid carcinoma. There is an increased risk ofrecurrence

after thyroidectomy because thyroid cells are highly active

in the young. Children and adolescents should be treated withanti-thyroid drugs until the late teens, failing which total or

near-total thyroidectomy by an expert surgeon should beundertaken.


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Follicular adenoma

Follicular carcinoma

Papillary carcinoma

Anaplastic carcinoma

Medullary carcinoma

Lymphoma

Metastatic

Local infiltration


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Follicular adenomas present as clinically solitary nodules and thedistinction between a follicular carcinoma and an adenoma canonly be made by histological examination; in the adenoma thereis no invasion of the capsule or of pericapsular blood vessels.Treatment is therefore by wide excision, i.e. lobectomy. Theremaining thyroid tissue is normal so that prolonged follow-up isunnecessary.

It is doubtful if there is such an entity as a papillary adenoma andall papillary tumours should be considered as malignant, even ifencapsulated.


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Papillary carcinoma 60 Medullary carcinoma 5

Follicular carcinoma 20 Malignant lymphoma 5

Anaplastic carcinoma 10


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The single most important etiological factor in differentiatedthyroid carcinoma, particularly papillary carcinoma, isirradiation of the thyroid under 5 years of age.

The incidence of follicular carcinoma is high in endemicgoitrous areas, possibly as a result of TSH stimulation.

Malignant lymphomas sometimes develop in autoimmunethyroiditis, and the lymphocytic infiltration in theautoimmune process may be an etiological factor.

Tumournodemetastasis staging (5th edition) of thyroid cancer

T


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TumourTX Primary cannot be assessed

T0 No evidence of primary

T1 Limited to thyroid, 1 cm or less

T2 Limited to thyroid, > 1 cm but < 4 cm

T3 Limited to thyroid, > 4 cm

T4 Extending beyond capsule, any size

NodesNX Cannot be assessed

N0 No regional node metastases

N1 Regional node metastases

MetastasesMX Cannot be assessed

M0 No metastases

M1 Metastases present

Stage Under 45 years Over 45 yearsI Any T, any N, M0 T1, N0, M0

II Any T, any N, M1 T2, N0, M0 or T3, N0, M0

III T4, N0, M0 or any T, N1, M0

IV Any T, any N, M1

Note the effect of age on stage; only patients older than 45 years can have stage

III or IV disease.


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Commonest tumor Spread to the lymph nodes is common but

blood-borne metastases are unusual unlessthe tumour is extrathyroidal. The term

extrathyroidal indicates that the primarytumour has infiltrated through the capsule ofthe thyroid gland


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They are differentiated from follicularadenomas by capsular and vascular invasion.

Lymph node involvement is much lesscommon than in papillary carcinoma. Blood-

borne metastases are more common and theeventual mortality rate is twice that ofpapillary cancer.


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Total thyroidectomy and appropriate nodalsurgery followed by radioiodine ablation withlong-term TSH suppression.


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Extremely aggressive ; arises from follicular cells ; occursmainly in elderly women. Local infiltration is an early featureof these tumors, with spread by lymphatic and by thebloodstream. They are extremely lethal tumors and survival iscalculated in months.

Complete resection is justified if the disease appears confinedto the thyroid and possibly the strap muscles and is onlypossible in a minority of patients. Even then the survivalrarely exceeds 6 months and the median is around 3 monthsfor the whole group.


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Lymphoma can present as a thyroid masslesion and is treated similarly to lymphomasof other body sites (chemotherapy,radiation).Isthmusectomy is rarely required to relieve

airway obstruction.


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These are tumours of the parafollicular cells (C cells) derived from the neuralcrest and not of cells of the thyroid follicle, as is the case for other primarythyroid carcinomas. The cells are not unlike those of a carcinoid tumour andthere is a characteristic amyloid stroma .

High levels of serum calcitonin and carcinoembryonic antigen (CEA) areproduced by many medullary tumours. Levels fall after resection and rise

again with recurrence making it a valuable tumour marker in the follow-up ofpatients with this disease.

Diarrhoea is a feature in 30% of cases and this may be due to 5-hydroxytryptamine or prostaglandins produced by the tumour cells.

Some tumors are familial, possibly accounting for 1020% ofall cases The familial form of the disease frequently affects


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all cases. The familial form of the disease frequently affectschildren and young adults, whereas sporadic cases occur atany age with no sex predominance.

Medullary carcinoma may occur in combination with adrenal

phaeochromocytoma and hyperparathyroidism (HPT) (usuallydue to hyperplasia) in the syndrome known as multipleendocrine neoplasia type 2A (MEN-2A).

When the familial form is associated with prominent mucosalneuromas involving the lips, tongue and inner aspect of the

eyelids, with a marfanoid habitus, the syndrome is referred toas MEN type 2B

Involvement of lymph nodes occurs in 5060% of cases ofmedullary carcinoma and blood-borne metastases arecommon. As would be expected, tumours are not TSHdependent and do not take up radioactive iodine. Theprognosis is variable and depends on the stage at diagnosis.

Any nodal involvement virtually eliminates the prospect ofcure and, unfortunately, even small tumours confined to thethyroid gland may have spread by the time of diagnosis,particularly in familial cancers.


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Treatment is by total thyroidectomy and either prophylactic ortherapeutic resection of the central and bilateral cervical lymphnodes.

Familial cases are now detected by genetic screening for RETgenemutations, which identifies individuals who will develop medullarycancer later in life .The genetic tests are supplemented by

estimating serum calcitonin levels. Prophylactic surgery is now recommended for infants with the

genetic trait.


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All thyroid operations can be assembled from three basicelements:Total lobectomy

Isthmusectomy

Subtotal lobectomy

Total thyroidectomy = 2 total lobectomy +isthmusectomySubtotal thyroidectomy = 2 subtotal lobectomy +isthmusectomy

Near-total thryroidectomy = total lobectomy +isthmusectomy + subtotallobectomyLobectomy = total lobectomy + isthmusectomy


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In thyrotoxicosis, drugs are given preoperatively to abolish thesymptoms including carbimazole and beta blockers; beta blockershave quicker onset of action.

Iodide is given for 10 days before surgery to decrease the vascularityof thyroid.

Laryngoscopy to assess the functions of vocal cords.

Informed consent.

Operation done under general anesthesia.


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oHaemorrhage

Tension haematoma deep to the cervical fascia isusually due to

reactionary haemorrhage from one of the thyroid arteries;occasionally, haemorrhage from a thyroid remnant or a

thyroid vein may be responsible. This is a rare but desperate

emergency requiring urgent decompression by opening the layers of

the wound, not simply the skin closure, to relieve tension before

urgent transfer to theatre to secure the bleeding vessel.


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may be unilateral or bilateral, transient or permanent.


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may be unilateral or bilateral, transient or permanent.

This leads to loss of tension in the vocal cord with diminished

power and range in the voice. Patients, particularly those who

use their voices professionally, must be advised that anythyroid operation will result in change to the voice even in theabsence of nerve trauma.

It occurs if a thyrotoxic patient has beeninadequately prepared for thyroidectomy. Symptomatic andsupportive treatment is for dehydration, hyperpyrexia andrestlessness.


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Most common form of chronic thyroiditis.

Associated with raised titres of thyroid antibodies. There is a familyhistory of other autoimmune disease.

It commonly presents as a goitre, which may be diffuse or nodularwith a characteristic bosselated feel, or with established orsubclinical thyroid failure.

The diagnosis often follows investigation of a discrete swelling.

The disease is most common in women at the menopause but mayoccur at any age. Papillary carcinoma and malignant lymphoma areoccasionally associated with autoimmune thyroiditis.

Treatment

Thyroxine replacement if there is hypothroidism

If long standing goitre of Hashimotos disease undergoes recentincrease in size , than urgent assessment to rule out lymphoma is

needed. Uncommonly throidectomy may be required if goiter is large and

causing discomfort.


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Caused by a viral infection. In a typical subacute presentation there is pain inthe neck, fever, malaise and a firm irregular enlargement of one or boththyroid lobes.

Raised ESR and absent thyroid antibodies, the serum T4 is high normal orslightly raised and the iodine uptake of the gland is low.

The condition is self-limiting and after a few months the goitre subsides andthere may be a period of months of hypothyroidism before eventual recovery.

In 10% of cases the onset is acute, the goitre is very painful and tender andthere may be symptoms of hyperthyroidism.

One-third of cases are asymptomatic but for the presence of the goitre. Ifdiagnosis is in doubt it may be confirmed by FNAC, radioactive iodine uptakeand a rapid symptomatic response to prednisone.

The specific treatment for the acute case with severe pain is to give

prednisone l020 mg daily for 7 days, with the dose gradually reduced overthe next month. If hypothroidism is prominent, treatment with thyroxine maybe required until function recovers.


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Riedels thyroiditis is very rare, accounting for 0.5% of goitres.

Thyroid tissue is replaced by cellular fibrous tissue, which infiltrates

through the capsule into muscles and adjacent structures, including

the parathyroids, recurrent nerves and carotid sheath.

It may occur in association with retroperitoneal and mediastinal

fibrosis and is most probably a collagen disease.

The goitre may be unilateral or bilateral and is very hard and fixed.The differential diagnosis from anaplastic carcinoma can be made

with certainty only by biopsy, when a wedge of the isthmus shouldalso be removed to free the trachea.

If the condition is unilateral the other lobe is usually involved laterand subsequent hypothyroidism is common.

Treatment is with high-dose steroids and thyroxine replacement.


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Thyroglossal cysts (TGCs) represent the most common congenital anomalyof the neck, accounting for 2-4% of all neck masses.

Arise from a persistent epithelial tract, the thyroglossal duct, formedwith the descent of the thyroid from the foramen caecum to its finalposition in the front of the neck.

The duct so formed can give rise to sinuses, fistulae, or cysts.

Symptoms can arise from the swelling itself or from complications,the most significant of which is infection.

Most commonly, they present in the first decade of life. However,they are also seen in adults


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Thyroglossal cysts (TGCs) usually present as fluctuantswellings in the midline of the neck along the line of thyroiddescent. : it is important to note that the cyst movesupwards on swallowing as well as when the patient protrudesthe tongue.

TGCs are usually non-tender and mobile. Infected TGCs may present as a tender mass.

A tender infected TGC may be associated with dysphagia,dysphonia, draining sinus, fever, or increasing neck mass.

An infected TGC may present like an upper respiratory tract

infection. Airway obstruction is possible, particularly with intralingual

cysts close to the airway.

Carcinoma may develop in thyroglossal duct cyst (about 1%of cases) (most commonly papillary carcinoma )


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Infrahyoid type 65% and is mostly found in the paramedian position

Suprahyoid type

Nearly 20% and is positioned in the midline

Juxtahyoid cysts

15% Intralingual location

2%

Suprasternal variety

10% of cases

Intralaryngeal

Very rare


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Surgical treatment of choice for thyroglossal cystsis the Sistrunk operation

Includes dissection of the hyoid bone and the base ofthe tongue

Recurrence is approximately 3-5% and is increased

by incomplete excision and a history of recurrentinfections

5.Thyroid Gland Lecture

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