Download Thyroid gland

Thyroid gland
Anatomy
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Bi-lobed gland over second and third
tracheal ring
piramidal lobe : 40 – 50 %
Weight : 20 – 30 gr
Epithelium lined follicle
Colloid : glycoprotein ( thyroglobulin )
Vascular stroma
True connective tissue capsule
It is important to ligate the superior
thyroid artery close to the gland to
avoid injury to the nerve during
thyroidectomy
Inferior thyroid artery
Inferior thyroid artery :
Thyrocervical trunk
Absent in up to 6%
 Thyroidea ima :
directly from aorta , innominate artery or
right common carotid artery
 Present in up to 12%
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Superior thyroid vein : IJV or common facial
vein
Inferior jugular vein : innominate vein or IJV
Middle thyroid vein : IJV
Lymphatic → paratracheal nodes → superior
mediastinum & middle deep cervical node
and lateral the neck
Embryology
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Median endodermal derivative that migrates
from the tongue base to its normal position in
the neck by 7th week .
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The distal portion of this thyroglossal duct
forms the thyroid gland
Physiology
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Concentrate iodine
20 – 30 % is store in thyroid
Small percentage in hormone and nonthyroid
tissue
All tyrosine compounds are bound to
thyroglubulin and store in thyroid follicles as
colloid
The unbound thyroid hormone is responsible
for influencing metabolism .
Thyroglossal duct anomaly
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7% of the population has remnants of the
thyroglossal duct
Cyst : anywhere along the length of duct
60% infrahyoid , 24% suprahyoid ,
1% intralingual
1-2 cm cystic mass that is mobile on
swallowing & protruding of the tongue
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60% contain thyroid tissue
Malignancy is rare
Acute infection
Contain mucus like clear fluid
If it is become symptomatic it must be
removed
Sistrunk operation
Lingual thyroid
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Failure of thyroglossal duct to descend
A mass at the foramen cecum
Aysmptomatic or present with airway
obstruction
May be the only thyroid tissue
Ectopic thyroid tissue
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Anywhere along the migratory route of the
thyroid
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Mediastinum , larynx , trachea , pericardium
or esophagus
Congenital intrathyroid cysts
Present in children persistent ultimobranchial
bodies or an intrathyroidal thyroglossal duct
cyst
Infectious and inflammatory
disorder
Acute suppurative thyroiditis
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M=F
Preceded by an upper respiratory tract
infection
Staph. The most common organism
Painful enlargement of the gland
Fever
Abscess formation
Painless thyroiditis
Sporadic form
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More common in female
Difuse thyroid enlarement
Without pain or thyroid enlargement
Temporary hyperthyroidism
50% become hypothyroid which resolves in
6 month
Postpartum thyroiditis
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Initial hypothyroidism is mild
Lymphocytic infiltration and follicle disruption
Self-limiting disease
Steroid may be of value
Subacute thyroiditis
( De Quervain´thyroiditis )
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At all age most common at 5th decade
F>M
May be viral
Painful thyroiditis
Defuse thyroid enlargement
Malaise and fever
thyrotoxic
Endocrine phases
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Hyperthyroidism : 1-3 month
Euthyroid : 1-3 weeks
Hypothyroid : 2-6 month
Recovery which is complete
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Lymphocyte , monoycyte and giant cell
infiltration .
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Treatment consist of analgesic steroid and
antiinflammatory agents .
Hashimoto´s thyroiditis
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Common
Affecting 2 population
95 % in female Autoimmune etiology with
strong genetic predisposition
Diffusely enlarge with nodularity firm
Disrupted follicle with lymphocyte and
plasma cell infiltration and variable fibrosis
Residual hypothyroidism
A thyroid scan demonstrated a
salt and pepper pattern
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Anti thyroglobulin and antimicrosomsal ab
are present up to 90%
FNA is diagnostic
Increased risk for developing B – cell
lymphoma
Riedel‘s thyroiditis
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Uncommon
F>M
Older patient
May be mediastinal & retroperitoneal fibrosis
Fixed rock-hard thyroid enlargement
Gland replaced with fibrosisAirway obstruction and
dysphagia
Palliative surgery to relieve obstruction
Hyperthyroidism
Graves‘ Disease
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3th and 4th decade
F/M : 7/1
Autoimmune etiology : abnormal Ig that fix on
TSH receptor of thyroid epithelial cell
Diffuse toxic goiter
ophthalmopathy 55%
Dermophathy 5%
Cont.
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↑ T3 , T4 , T3RU
Thionamide , sympathetic blocker , iodine
Radioactive iodine
Pregnant women should not be
treated with this modility
Surgical indication
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Refuse radioactive therapy
Thyroid nodules suspicious for malignancy
Must be rendered euthyroid prior to surgery
Subtotal thyroidectomy leaving 7-8 gr of
nodule free tissue is recommended
however , total thyroidectomy is proposed
by many
Toxic multinodular goiter
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Older patient no ophthalmopathy or
dermophathy
Total thyroidectomy
Radioactive iodine but not successfully as
surgery
Toxic adenoma
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Younger patient Quite large ( 2.5 – 3 cm )
Surgical excision
Multinodular nontoxic goiter
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Compensatory response
Common in female Secondary to dietry
deficiency
Symptom and sign of pressure
A small percentage (1-2%) may
harbor a malignancy
Treatment
Thyroid suppression
 Surgery:
cosmetic deformity
pressure symptom refractory to suppression
Fear of malignancy
Development of toxicity
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Neoplasm & Cyst
Benign adenoma
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Encapsulated tumor
Glandular epithelium with intratumoral
degenerative changes ( hemorrhage ,
fibrosis , calcification )
Rare thyrotoxicosis
Type : follicular,colloid , embryonal, fetal ,
Hurthle ???
Malignant
Papillary carcinoma
60 – 65 %
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Third – 5th decade
F/M : 2/1
Indolent with overall excellent prognosis
May arise from benign adenoma
Low-dose and high dose external RT
Macroscopic pattern
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Occult ; <1.5 cm
Intrathyroid ( 70% )
Extrathyroid : infiltrate larynx , trachea , strap
muscle , great vessel
Microscopic pattern
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Purely papillary
Some may have area of follicular
Anaplastic transformation is rar
Venous invasion in 10%
Intraglandular lymphatic invasion
results in high incidence of
multicentricity
Neither multicentricity nor regional LN
metastasis have any prognostic
significance
Negative prognostic indicator
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Advance age
Male gender
extrathyroid extension
Distant metastasis
Cont.
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Dedifferentiation
Vascular invasion
Atypical variants ( tall cell, columnar ,
sclerosing ) may have negative prognostic
significance
Follicular carcinoma
15%
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Vascular invasion
Metastasis to bone brain and liver
Anaplastic transformation is more common
Overtly invasive : infiltrate surrounding
structure ( MR 20-50%)
Minimally invasive : microscopically has
capsular invasion (MR 5%)
Definitive diagnosis can often be
established only on permanent
section
Poor prognostic indicator
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Advanced age
Male gender extrathyroid extension
Distant metastasis
Vascular invasion
anaplastic transformation trabecular growth
pattern
Hurthle cell carcinoma
5%
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As a variant of follicular tumors
Overtly invasive :higher mortality rate
Higher LN metastasis
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Minimally invasive
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Not all nodule containing Hurthle cell are
neoplastic .The vast majority are Hurtule
cell changes in benign follicular
adenomatous nodules or thyroiditis
Medullary carcinoma
3-5%
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10 – 20 % familial
Sporadic : in 5th decade
Multicentric ,lateral upper 2/3 of gland
Encapsulated , diffuse infiltrative
50% nodal metastasis
15-25% distant metastasis
MEN type 2A
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Medullary thyroid cancer
C-cell hyperplasia
Adrenal pheochromocytoma
Adrenal medullary hyperplasia
Parathyroid hyperplasia
MEN type 2B
In addition :
 Mucosal neuromas
 GI ganglioneuroma
 Musculoskeletal abnormality
Poor prognostic indicator
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MEN type 2B
Nodal & distant metastasis
Extrathyroid extension
Small cell tumor pleomorphism
Poor calcitonin staining
High CEA
Anaplastic carcinoma
1-5%
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Rare tumor
Arise in well-differentiated tumor
Older women
Advance stage early infiltration of
surrounding structure
Small cell , giant cell
Extremely poor prognosis
Lymphoma
1-3.5%
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Primarily in the thyroid
As a part of systemic disease
Arises in a gland with Hashimoto´s thyroiditis
Elderly women
Diffusely enlarged gland or nodule
Hypothyroidism
Diffuse large cell lymphoma
Good prognosis
Miscellaneous
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Sarcoma
Mucoepidermoid carcinoma
SCC
Kidney , colon , melanoma are the most
common distant site
Clinical presentation
Thyroid enlargement
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Smooth and diffuse ( usually benign )
Nodular
Multinodular goiter may harbor a neoplasm(
10-15% ) :
90% benign
10 % malignent
Overall incidence of malignancy in a
multinodular goiter is only 1-2%
Symptom & sign of pressure
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Dysphagia ( discomfort on swallowing →
obstruction )
Mild to moderate stridor → chondromalacia
→ airway obstruction
TVC edema & RLN paralysis → hoarseness
Retrosternal extension → tracheal deviation
& SVC
Symptom & sign of infiltration
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Stridor and hemoptysis
Rapid increasing in mass
RLN paralysis
Dysphagia & odynophagia
Brachial plexus infiltration
Painful enlargement
Evidence of regional and distant
metastasis
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It is the only obvious clinical evidence of
thyroid cancer
Papillary metastasis may be cystic ( 20%)
Follicular carcinoma : distant metastasis
Medullary and anaplastic : extracapsular
extension
Evidence of endocrine dysfunction
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Most patients are euthyroid
Occasionally : hypothyroid
Rarely : hyperthyroid
Medullary : ↑ calcitonin , ACTH , PG
secretion
Evaluation of a thyroid mass
Neck X-ray
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Patchy calcification :
Benign thyroid disease
Well –differentiated carcinoma
Medullary carcinoma
Chest X-Ray
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Retrosternal extension
Tracheal deviation
Mediastinal nodal involvement
Pulmonary metastasis
CXR should always be done
Esophagogram
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It should be done if the patient complains of
significant dysphagia
It differentiate thyroid from nonthyroid causes
of dysphagia
Radionuclide scan
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Determine the functional status of gland
Differentiate diffusely enlarge from nodular
Differentiate single nodule from multinodular
goiter
Tc-99
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Low cost
Ready available
Short – half life
Optimal imaging
Only trapped , not organified
Radioactive Iodine
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It is able to determine function
¹²³I is the best but is expensive and have very
short half life
Thallium 201
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Detecting :
lymph node metastasis
retrosrernal extension
recurrent disease functioning
nodule within suppressed gland
Octreotide scintigraphy is useful for
detecting metastatic medullary and
Hurthle cell carcinoma
Radionuclide scan no longer used as
a first line imaging study
Ultrasonography
High – resolution real time US enable
the radiologist to detect nodule as
small as 3mm
US usage
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Screening high risk patient ( prior RT )
Differentiating single nodule from multiple
Cystic or solid status
Facilitating FNA
Monitoring medically treated patient
Evaluating clinically negative neck for
metastasis
Recurrent disease after surgery
CT scaning & MRI
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Extrathyroidal extension
Retrosternal involvement
Metastatic disease
Unnecessary in the evaluation of a routine
thyroid mass
Metastatic workup
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Bone scan
CT scan of abdomen and chest
Octreotide study
Blood test
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T3
T4
TSH
Thyroid Ab for Hashimoto thyroiditis
Serum thyroglobulin
Serum calcitonin in medullary carcinoma
especially if there is a family history
These level may increases after FNA
and should be performed prior to it
Postoperative serum thyroglobulin
levels under 10 ng/ml in patients
under supression therapy are
indicative of cancer control
FNA biopsy
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Obtain satisfactory specimen from nodule
it is of no value in microinvasive follicular
If the report is suspicious the patient should
probably proceed to surgery
Inadequate specimen repeat FNA
FNA biopsy
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The best results obtains from periphery
Multiple aspirates are frequently necessary
A negative FNA should never preclude
surgical exploration in a patient with
highly suspicious lesion
Large bore needle aspiration
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A portion of capsule and surrounding tissue
can be included
It is rarely indicated
Surgical exploration
indication
Obvious malignancy
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Clinical or radiographic evidence of
infiltration
Clinical or radiographic evidence of regional
or distant metastasis
FNA positive for malignancy ( papillary ,
medullary , anaplastic )
Thyroid mass with raised serum level of
calcitonin
Suspicion of malignancy
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Suspicious fine – needle aspiration
Nodule refractory to suppression
Solitary thyroid nodule with raised serum
thyroglobulin level
Recurrent cyst refractory to two aspirations and
thyroid suppression
Nodule going wrong , a solitary nodule increasing in
size and associated with pain
True single nodule in males elderly women children ,
or in any patient with a history of prior RT
Management of thyroid Tumor
Every patient undergoing a thyroid
exploration should sign a very specific
detail and inform that should include
the possibility of performing
throidectomy
Total thyroidectomy
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Better oncologic operation in the case of
multicentric disease
Difficult residual thyroid suppression and
anaplastic transformation risk
Good postoperative scanning and radioactive
ablation
Postoperative thyroglobulin titrage
Subtotal thyroidectomy
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Simpler & time –consuming
Lower morbidity
Not affected the prognosis of well
differentiated tumor
Extrathyroid extension
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Well-differentiated tumor : 9-16%
If gross tumor would be left using the shaving
technique wild field resection should be
performed .
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RLN enveloped & paralyzed it should be
sacrificed .
If it is the only functioning nerve and the
tumor and the tumor can be dissected off this
should be done
Superficial invasion can be shaved but
direct extension into the lumen :
sleeve or wedge resection and primary
anastomosis
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Superficial thyroid cartilage : shave resection
Hemilarynx : vertical partial laryngectomy
Anterior larynx : hemilaryngectomy And
reconstruction
Cricoid and bilateral laryngeal involvement :
total laryngectomy
Postoperative RT and iodine is
indicated
Regional lymph node
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In all patient : pericapsular and paratracheal
node need to be removed routinely
Overt node in these area : sup. Mediastimun
and lateral neck exploration
Papillary carcinoma
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Clinical node : 20-25%
Pathological node : 30-79%
It has no adverse effect on prognosis
Extracapsular extension does not appear to
have an ominous prognosis
Follicular carcinoma
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Very rare < 10% clinically & 20%
pathologically
Neck dissection are performed only for overt
metastasis
Hurthle cell carcinoma
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30% lymphatic metastasis
Functional neck dissection should be
performed when disease is encountered
Medullary carcinoma
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Metastasis : 50 – 63 %
Prophylactic paratracheal , superior
mediastinal and lateral neck dissection
Or : positive node in mediastinum and lateral
neck dissection is performed
Follow -up
Well-differentiated tumor
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Become hypothyroid and after 4-6 week
radioiodine scan
Any residual tissue : I ablation
In overt local or regional remnant & distant
metastasis should be used
Further 6 and 12 months scan and then
every 2 year
Serum thyroglobulin every 6 months
Medullary carcinoma
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Calcitonin level : every 3 months ( in first
year )
Every six months there after
High calcitonin level : full metastatic work up
CT & MRI of the neck and octreotide scan
No overt disease : neck dissection and if it
done before RT to neck
Postoperative RT
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Residual and inoperable disease or cancer that has
undergone anaplastic transformation
50 Gy
RT appears more effective than radioactive iodine in
treating local recurrence in WD cancer
I radioactive is the treatment of choice for distant
metastasis
RT is the treatment of choice in anaplastic carcinoma
Role of chemotherapy
Most disappointing results
Postoperative thyroid hormone
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Total thyroid ablation : T4 supplement
It is useful in controlling any microscopic
residual WD thyroid cancer that may have
been left locally , regionally or distantly
Prognosis
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Low risk patient : 1-2 % MR
High risk patient : 40 – 50 %
Hereditary & sporadic cancer have similar
survival ( 82% at 5 year )
Anaplastic cancer has a dismal survival
Early stage medullary : good prognosis