approach to a thyroid nodule
DESCRIPTION
Approach to a thyroid nodule. According to american thyroid association guidelines 2005-2006. Anatomy of the Thyroid Gland. Follicles: the Functional Units of the Thyroid Gland. Follicles Are the Sites Where Key Thyroid Elements Function: Thyroglobulin (Tg) Tyrosine Iodine - PowerPoint PPT PresentationTRANSCRIPT
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Approach to a thyroid nodule
According to american thyroid association guidelines 2005-2006
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Anatomy of the Thyroid Gland
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Follicles Are the Sites Where Key Thyroid Elements Function:
• Thyroglobulin (Tg)
• Tyrosine
• Iodine
• Thyroxine (T4)
• Triiodotyrosine (T3)
Follicles: the Functional Units of the Thyroid Gland
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Thyroid Hormones
Thyroid pro-hormone is stored as thryoglobulin as an extracellular colloid
T3 and T4 can cross lipid membranes readily (secretion and uptake)
T3 and T4 are small, hydrophobic and circulate bound to Thyroxine-binding globulin (TBG)
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Hypo – Pit-Thyroid Axis
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Approach
Clinical.Biochemical.Radiological.Histopathological.
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Clincal
History taking.
Physical examination.
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History
Profile. Mass in ant. neck (onset, duration, pain,
course, trauma….) Assessment of function( Symptoms of
thyrotxicosis or hypothyroidism) Risk factors for malignancy. Review of Systems, medical hx., past hx,
drug hx, social hx.
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Symptoms of thyrotoxicosis
nervousness, tremors, sweating, heat intolerance, palpitations, wt loss despite normal or increased appetite, amenorrhea, weakness.
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Hypothyroidism
Lethargy, hoarseness, hearing loss, thick and dry skin, constipation, cold intolerance, stiff gate, weight gain.
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Risk factors for malignancy
Age sexoccupationfamily hxPainlessHoarsenessHx of irradiationhard,LN enlargementresidency,...............etc.
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Physical Exam
Swelling in the anatomical site of thyroid.
Moves with swallowing
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Goitre
Diffuse
Nodular
-Solitary nodule
-Multinodular goitre
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Anatomical dx includes
retrosternal extension
extension below sternocledomastoid
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Solitary Noudule
Neoplastic
Non neoplastic
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Non Neoplastic
Cyst: degenerative, Haemorrhogic, Hydatid…
Surgery is indicated after second reccurence.
Solid : Part of Multinodular Goitre.
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Neoplastic
Benign: Follicular adenoma
Malignant: Wide spectrum of behaviour
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Papillary Ca
Most common, Best prognosis 10 year survival around 85 % At younger age group. Spreads by lymphatics. Can be multifocal. Can be familial. Usually sensitive to RAI
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Follicular Ca
10 y survival around 60 %. Associated with iodine deficiency. Usually monofocal. Haematogenous spread. Diagnosed by capsular and vascular
infiltration. Sensitive to RAI.
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Medullary Ca
From Parafollicular cells. 10 year survival 25-30% Can be Familial or Sporadic. Can be part of MEN 2. Does not uptake RAI.
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Anaplastic
Around 1 % Very aggressive tumor. The worst prognosis Survival is usually less than 6 months
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Fibrolymphovasclar tumors
Haemangioma, Lymphoma, Fibroma,…..
Secondary Metastases.
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Biochemical
Thyroid function tests: T3, T4, TSH.
Antithyroid Antibodies: antithyroglobulin, antimicrosomal antibodies.
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Imaging Assessment
Ultrasound.
Computerized tomographic scan.
Magnetic resonance scan.
Radioactive Iodine scan.
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Pathological Dx
Fine Needle Aspiration.
Surgery for definitive biopsy.
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Ultrasound
One nodule or more
Cystic or solid
Presence or abecence of features of malignancy
Cervical LN enlargement
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Features of malignancy in U/S
Microcalcification.
Hypoechoeic nodules.
Increased vascularity.
Interupted hallo sign
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U/S guided FNA
Prefered if
- > 50 % cystic leision.
- located posteriorly.
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Serum Thyroglobulin
Increases in most thyroid pathologies.
Not specific as a diagnostic tool.
For follow up only.
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Serum Calcitonin
Contraversy about its importance as a diagnostic tool.
if >100 pg/ml can suggest medullary Ca.
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Benign FNA
Risk of false neg. Up to 5%.
papable >U/S guided(0.6%).- Repeat examination or U/S 6-18 m interval- Growth>20%,or more than 2mm in two
dimensionsrepeat FNA preferably U/S guided.
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Medical Treatment
No data to suggest that TSH suppression will cause a change in thyroid nodule size in Iodine sufficient area.
Not recomended.
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Children
Should be evaluated as adults.
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Pregnancy
Thyroid scan should be delayed till delivery. If operation is to be done 12-24wks GA. After that should be postponed till delivery. (studies:delay less than one year will not
affect the eventual prognosis)
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Treatment
Goals: 1-to remove the primary tumour and its
local extension. 2-to minimize treatment related morbidity. 3-to permit accurate staging. 4-fascilitate postop. Radioactive Iodine ttt. 5-fascilitate long term postop. Surveilance 6-minimize disease reccurence and mets.
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Total Thyroidectomy
1- FNA papillary,medullary.
2- nodule > 4cm and atypia.
3- hx. Of irradiation or positive family hx.
4- bilateral nodules.
5- regional LN or distant metastases.
6- patient preferance for one stage.
7- relative indicationage >45
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Lobectomy
Soitary nodule+indetermined pathology FNA+ patient preferance.
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Central LN Dissection
– CLN are most common site of recurrence.
Routine CLN dissection is indicated in medullary Ca., no consensus in papillary Ca.
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Lateral Neck Dissection
Levels II,III,IV and V
Done only with biopsy proven metastases after clinical or sonographic suspicion
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Completion Thyroidectomy
To allow resection of multicentric disease. Allow radioactive Iodine diagnostic scan and
treatment. Studies:same surgical risk as one stage
surgery. (small tumours<1cm,intrathyroid,node
neg.,low risk group) can be managed without completion.
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Postoperative Radioactive Iodine Ablation
Prepared with L-thyroxin withdrawal for 4 wks,or replace it with T3 for 2-4 wks then withdraw it for 2 wks.
TSH > 30, to increase avidity. The minimal activity should be used 30-100 mci. Higher dose 100-200, in residual disease or
aggressive pathology(tall cell,columnar,insular)
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Recombinant human thyrotropin(rhTSH) can be used in patients who cannot tolerate stopping thyroxin.
Needs stopping thyroxin for one day only.
Approved in Europe but still not in USA.
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Whole body scan
Usually done one week after ablation therapy.
10-26% metastatic foci.
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External Beam Radiotherapy
Indications
- age > 45 and extrathyroid extension and high likelyhood of microscopic residual tumour.
-gross residual and further surgery or radioactive iodine treatment is ineffective.
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Chemotherapy
NO role for chemotherapy in differentiated thyroid Ca.
Some studies:Adriamycin can act as a radiation sensitizer for external beam radiotherapy.
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TSH Suppression Therapy
Differntiated thyroid Ca have TSH receptors on cellular membrane.
High risk patients < 0.1 mu/l
Low risk patients 0.1 - 0.5 mu/l
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Prognosis
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Follow Up
Every 6-12 months. Physical examination and cervical U/S Thyroglobulin and calcitonin. In borderline Tgn stimulation by
withdrawing thyroxin or rhTSH. If positive whole body scan