Thyroid and Parathyroids————————————————

Thyroid and Parathyroids
Diana Marie D. Ampuan, MD, MPM

THYROID GLAND
 Endocrine gland in the neck
 Produces thyroid hormones: T3 and T4
 thyreoeides, shield – shaped

Embryology
 outpouching of the primitive foregut around 3rd
week of gestation
 Originates at the base of the tongue at the foramen cecum
 Endoderm cells in the floor of pharyngeal anlage thicken to form medial
thyroid anlage that descends in the neck anterior to the future hyoid bone
and larynx
 During descent, anlage remains connected to the foramen cecum via and
epithelial-lined tube – known as the THYROGLOSSAL DUCT
 Paired lateral anlage from 4th
branchial pouch and fuse with the median
anlage at 5th
week of gestation
 Lateral anlage – neuroectodermal in orogin (ultimobranchial bodies) – c cells
or parafollicular cells which secretes calcitonin (which lie in the superoposterior
region of the gland)
 Thyroid follicles are apparent in 8 weeks
 Colloid formation by 11th
week

THYROGLOSSAL DUCT CYST
PATHOPHYSIOLOGY CLINICAL MANIFESTATIONS MANAGEMENT
Persistence of the thyroglossal
duct anywhere along its migratory
path (normally disappears by the
8th
week of gestation)
May persist as whole or as part
With heterotrophic thyroid tissue in
20% of cases
• Usually asymptomatic, may be
infected by bacteria
• 1-2 cm, smooth, well-defined,
palpable midline mass on the
neck that moves upward when
the tongue is protruded
• 1% will have malignancy;
usually papillary thyroid cancer
• Anywhere in the migratory
tract, 80% juxtaposition to hyoid
bone
Sistrunk operation: excision of the
entire cyst and central hyoid
bone
Thyroidectomy – debated,
advised if with large tumors, add’l
thyroid nodules, cyst wall invasion
or lymph node metastases
Routine thyroid imaging not
necessary
Thyroid scintigraphy and
ultrasound – may be performed to
document normal thyroid tissue in
the neck

Lingual Thyroid
Ectopic thyroid tissue located
in the base of the tongue
Failure of descent of the thyroid
anlage
• Many patients are
hypothyroid
Exogenous thyroid hormone to
suppress TSH
RAI ablation, then hormone
replacement
Indication for surgery (rare):
obstructive symptoms like
dyspnea and dysphagia

Ectopic Thyroid
Normal thyroid tissue found in
other compartments of the neck
(esophagus, trachea, anterior
mediastinum, adjacent to aortic
arch, aortopulmonary window,
within the upper pericardium,
interventricular septum)
Thyroid tissue in Carotid sheath
and jugular vein (Lateral aberrant
thyroid)- represents metastatic
thyroid cancer in lymph nodes not
remnants of the anlage
Even if not apparent on PE or
imaging, ipsilateral thyroid lobe
contains focus of Papillary Thyroid
Carcinoma, maybe microscopic
• Most are asymptomatic
• Symptoms may be related
to size and relationship with
surrounding tissues
• Evaluation should consider
whether the ectopic tissue is
the sole active thyroid tissue
• Thyroid scintigraphy: to
diagnose activity
• For symptomatic disease:
surgery is the treatment of
choice

Pyramidal Lobe
 Thyroglossal duct atrophies – some remain as fibrous band
 50% - distal end of the thyroglossal duct connects to the
thyroid persists as pyramidal lobe projecting up to the
isthmus, left/right of the midline
 Not palpable normally
 But in hypertrophy - palpable

GROSS ANATOMY AND PARTS
 2 pear – shaped lobes connected by an isthmus
 Brown in color and firm in consistency
 Posterior the strap muscles
 50% w/ pyramidal lobe(remnant of the distal end of the thyroglossal
duct
 Weight : 20 g
 Pre – tracheal fascia attaches the gland to cricoid cartilage
(LIGAMENT OF BERRY)
 Thyroid lobes – adjacent to thyroid cartilage

Thyroid and Parathyroids————————————————

SONOGRAPHY OF NORMAL THYROID GLAND
 Mean length – 5cm
 Ap diameter 13-18 mm
 Isthmus thickness: 4-6 mm
 Volume : 18 mL in women and 25 mL in men
 Volume of each lobe is calculated using formula :
(L x W x D) x 0.5

LOCATION
5th
cervical vertebra to 1st
thoracic vertebra (C5 – T1)
Lobes are adjacent to thyroid cartilage
Isthmus lies anterior to the 2nd
, 3rd
and 4th
tracheal rings

Arterial supply
Artery from supplies
Superior thyroid artery external carotid artery upper 1/3 of lobe &
upper ½ of isthmus
Inferior thyroid artery thyrocervical trunk Lower 2/3 of lobe &
lower ½ of isthmus
Thyroidea ima artery – present in 1-4% of patients

VENOUS DRAINAGE
Vein Drains to
Superior and middle thyroid veins Internal jugular vein
Inferior thyroid vein Brachiocephalic vein

Lymphatic Drainage
 First echelon
 1. central compartment of the neck
 2. nodes of the superior mediastinum
 3. lateral cervical nodes
 Specific nodal groups that drain the thyroid in the level VII compartment
are the
 Paralaryngeal
 Paratracheal
 Prelaryngeal (Delphian nodes)
 Level VII nodes - those of the superior mediastinum that lie superior to the
innominate vein
 Lateral cervical nodes include nodes in both level III and IV

Histology
 Lobules – with 20-40 follicles
 Follicular cells (thyrocytes): produce, store and release
thyroid hormones (T3 and T4 under the influence of
TSH(anterior pituitary gland)
 Parafollicular cells (C cells): produce calcitonin, which
regulates serum calcium level

Nerve injury during thyroid surgery
 Laryngeal nerves – arise from the vagus nerve on each side
 Left recurrent laryngeal nerve (RLN): crosses arch of the aorta, loops around
ligament arteriosum, and ascends to the tracheoesophageal groove
 Right recurrent laryngeal nerve (RLN): crosses and loops around the
subclavian artery

Nerve injury during thyroid surgery
NERVE CLINICAL MANIFESTATION
RECURRENT LARYNGEAL NERVE (innervates all intrinsic muscles of the larynx except the cricothyroid)
UNILATERAL INJURY • Vocal cord in paramedium position: normal
voice but weak
• Vocal cord in abducted position: hoarse
voice, weak cough
BILATERAL INJURY • Airway obstruction (needs emergency
trancheostomy)
• Loss of voice
• If both cords are abducted: weak cough, risk
of aspiration and recurrent infection
SUPERIOR LARYNGEAL NERVE
INTERNAL BRANCH INJURY (provides sensation
above the vocal fold)
Risk of aspiration
EXTERNAL BRANCH INJURY • Cannot hit high notes or project the voice
• Voice fatigue after long speech
• Also called the “Amelita Galli Curci nerve”

IODINE METABOLISM
 Ave daily iodine requirement – 0.1 mg
 Iodine converted to iodide – Stomach and Jejunum ->
absorbed to bloodstream -> distributed to extracellular
space
 Iodide Transported to Thyroid Follicular cells (ATP
dependent process)
 THYROID
 storage site of 90% of body iodine content
 accounts to 1/3 of plasma iodine loss (2/3 plasma iodine
clearance – renal excretion)

Thyroid Hormone
Synthesis, Secretion and Transport

Thyroid Function Tests
 Serum TSH (Normal 0.5 – 5
 Total T4 (Reference Range 55-150 nmol/L)
 Total T3 (Reference Range 1.5-3.5 nmol/L)
 Free T4 (Reference Range 12-28 pmol/L)
 Free T3 (Reference Range 3-9 pmol/L)
 Thyrotropin – releaseing hormone - evaluation of pituitary TSH secretory function
 Thyroid antibodies
 Serum Thyroglobulin
 Serum Calcitonin (0-4 pg/mL Basal)

Radionuclide Imaging
 Iodine 123 (123
I)
 low dose radiation
 half life: 12-14 hrs
 Used to image lingual thyroids and goiters
 Iodine 131 (131
I)
 Higher dose radiation
 Half life: 8-10 days
 Used to screen and treat patents with differentiated thyroid cancers for metastatic disease
 COLD – areas that trap less radioactivity, higher risk of malignancy (20%)
 HOT – increased activity, lesser risk of malignancy (<5%)
 Technetium Tc 99m pertechnetate (99m
Tc) – taken up by the mitochondria – sensitive fr nodal
metastases
 F – fluorodeoxyglucose (FDG) positron emission tomography (PET) combined with CT
 Screen for metastases for patients with thyroid cancer whom other imaging are negative
 May show clinically occult thyroid lesions

Ultrasound
 Evaluation of thyroid nodules
 solid from cystic
 Size
 Multicentricity
 Echotexture
 Shape
 Borders
 Presence of calcifications
 Vascularity
 Cervical lymphadenopathy
 Guide FNAB

CT/MRI
 Excellent imaging of thyroid gland, adjacent nodes
 Evaluating extent of large, fixed or substernal goiters
 Relationship to the airway and vascular components
 Non – contrast CT scan for patients that will undergo RAI
therapy
 If contrast necessary, therapy delayed by several months
 Combined PET – CT – used for Tg-positive, RAI – negative
tumors

DISORDERS OF THE THYROID GLAND

PATHOPHYSIOLOGY
 Enlargement of the thyroid gland
 Diffuse, uninodular or multinodular
 Common cause: iodine deficiency leading to hyperplasia to compensate
for decreased efficacy

Clinical Manifestations
 Most are asymptomatic
 Large goiters may cause dyspnea or dysphagia
 Dysphonia – suspect malignancy (invasion of recurrent laryngeal nerve)
 Maybe associated with hypo/hyperthyroidism or euthyroid
 Acute pain or enlargement: hemorrhage

Clinical Evaluation of Thyroid size
GRADE DESCRIPTION
I No palpable or visible goiter
II Goiter palpable but not visible in
normal head position
III Goiter palpable and visible in normal
head position

Diagnosis
 Usually clinically euthyroid (normal TSH + low normal or normal free T4)
 FNAB: recommended if patient has a dominant nodule or if mass is painful or
increasing in size
 Ultrasound or CT scan to determine extent of goiter

Management
Nonsurgical Iodine supplementation for endemic goiter
Surgical Indications for near-total or total thyroidectomy +
lifelong T4 therapy
• Increase in size even with T4 suppression
• Significant mass effect causing obstruction
• Substernal extension
• To rule out malignancy
• Cosmetically deforming

Hyperthyroid states that may
benefit from surgery
HYPERTHYROID = low TSH and high free T4 and T3

DIFFUSE TOXIC GOITER (GRAVES DISEASE)
PATHOPHYSIOLOGY PRESENTATION DIAGNOSTICS MANAGEMENT
• Autoimmune disease
that targets thyroid
stimutaing hormone
receptors
• Strong familial
disposition
• Female
preponderance (5:1)
• Peak 40-60 yo
• Autoantibodies
stimulate growth of
thyrocytes with
increase in thyroid
hormone
• Possible triggers:
postpartum state,
iodine excess, lithium
therapy, bacterial and
viral infections
• Genetic
• Diffuse goiter with
thyrotoxicosis
• Systemic symptoms:
o Ophthalmopathy
(proptosis, chemosis,
visual loss)
o Dermopathy (pretibial
myxedema)
o Thyroid Acropachy
o Gynecomastia
o Heat intolerance
o Weight loss
o Diarrhea
o Palpitations
o Amenorrhea
• PE: diffusely enlarged
thyroid
• Diagnosis: suppressed
TSH + elevated FT4/FT3
• Opthalmopathy
present – no other
diagnostics needed
• If no eye signs, RAI
uptake
• Elevated uptake of
Iodine with diffusely
enlarged gland –
confirms diagnosis
• Elevated:
 Anti – Tg – not specific
 Anti – TPO – not
specific
 TSH –R - diagnostic
 TSAb – diagnostic
• CT/MRI of orbits
Options:
• Antithyroid
medications
(propylthiouracil (PTU)
or methimazole)
• Ablation using
radioactive iodine or
RAI (I131
)
• Near total or total
thyroidectomy

MULTINODULAR TOXIC GOITER
(Plummer disease)
PATHOPHYSIOLOGY PRESENTATION MANAGEMENT
• Nodules autonomously
produce hormones,
resulting to
hyperthyroidism
• Usually in older patients
with previous history of
multinodular nontoxic
goiter
• Similar to graves disease
but no systemic
symptoms
• Ablation using RAI (I131
)
• Near total or total
thyroidectomy

Toxic Adenoma or Solitary Toxic Nodule
• Single thyroid nodule that
is hyperfunctioning
• Younger patients
• Characterized by
mutations in the TSH – R
gene
• Nodule attained size of 3
cm before
hyperthyroidism occurs
• Palpable thyroid nodule
with normal contralateral
lobe
• Increased uptake (hot or
hyperfunctioning nodule)
on RAI scanning
• Small nodules antithyroid
medications, RAI, possible
percutaneous ethanol
injection
• Young patients with large
nodules: lobectomy and
isthmusectomy

Thyroid Storm
 Hyperthyroidism acoompanied by:
 Fever
 CNS agitation
 Depression
 Cardiovascular
 Gastrointestinal dysfunction – including hepatic failure
 Precipitated by abrupt cessation of anti - thyroid meds, infection, thyroid or non –
thyroid surgery, trauma in patients with untreated thyrotoxicosis
 Amiodarone administration or exposure to iodinated contrast agents or ff RAI
theraphy
 Beta – blockers can be given to reduce peripheral T4 to T3 conversion and decrease
symptoms
 O2 supplementation and hemodynamic support
 Non aspirin compounds used to treat pyrexia and Lugol’s iodine or sodium
ipodate(IV) – decrease iodine uptake and thyroid hormone secretion
 PTU – blocks formation of new thyroid hormones and reduces peripheral conversion
of T4 to T3
 Corticosteroids helpful to prevent adrenal exhaustion and block hepatic thyroid
hormone conversion

Hypothyroidism
 Deficiency of circulating
thyroid hormone levels
 In neonates, cretinism –
neurologic impairment and
mental retardation
 Pendred’s syndrome – assoc
with deafness
 Turner’s syndrome
 Clinical Features:
 Tiredness
 Weight gain
 Cold intolerance
 Constipation
 Menorrhagia
 Myxedema
 Facial and periorbital
puffiness
 Rough dry skin with
yellowish hue
 Hair dy and brittle
 Loss of outer 2/3 of
eyebrows
 Enlarged tongue –
impaired speech
 Impaired libido and
fertility
 Cardiovascular changes:
bradycardia,
cardiomegaly,
pericardial effusion,
reduced cardiac output,
pulmonary effusions

Acute Thyroiditis
• Suppurative infection from:
 Hematogenous
 lymphatic seeding
 persistent thyroglossal duct
cyst
 pyriform sinus fistulae
 penetrating trauma
 immunocompromised state
• Most common: streptococcus
and anaerobes (70%)
• More common in children
• Usually preceded by URTI
• Severe neck pain radiating to
the jaws/ear with fever, chills,
odynophagia, dysphonia
• Complications:
 Systemic sepsis
 Tracheal/esophageal rupture
 Jugular vein thrombosis
 Laryngeal chondritis
 Perichondritis
 Symphatetic trunk paralysis
• Persistent Pyriform sinus fistula -
suspected in children with
recurrent thyroiditis
• Diagnosis:
 Leukocytosis, FNAB for gram
stain, culture and cytology
 CT scan to delineate extent of
infection and identify abscess
• Antibiotics and drainage of
abscess
• Thyroidectomy for persistent
abscess
• Excision of fistula if present

Subacute or granulomatous
(de Quervain) Thyroiditis
• Exact etiology is unknown
• Presumed to be viral or a result
of postviral inflammation
• Genetic predisposition: HLA-
B35 haplotype
• Painful Thyroiditis: usually
preceded by upper respiratory
tract infection
• 30-40 yo women
• Sudden onset of neck pain
radiate toward mandible/ear
• 4 stages:
 Hyperthyroid
 Euthyroid
 Hypothyroid
 Euthyroid
• Painless thyroiditis:
• postpartum, more common in
30-60 yo women
• autoimmune
• Thyroid hormone replacement
(short term)
• Thyroidectomy – reserved for
rare patient with prolonged
course not responsive to
medical mgt and with
recurrent disease

Chronic Thyroiditis: Lymphocytic
(Hashimoto) Thyroiditis
• Autoimmune disorder in
which thyroid tissue is
diffusely infiltrated by
lymphocytes
• Destruction of thyrocytes by
cytotoxic T cells,
autoantibodies and natural
killer cells
• Directed against:
1. Tg (60%)
2. TPO (95%)
3. TSH – R (60%)
4. Na/I symporter (25%)
• Most common inflammatory
disorder of the thyroid and
cause of hypothyroidism
• More common in women
• Male to female ratio
(1:10 to 20)
• 30-50 yo
• Min or moderate
enlargement of the thyroid
• painless
• 20% hypothyroid, 5%
hyperthyroid(Hashitoxicosis)
• PE: diffusely enlarged gland
firm, lobulates
• Enlarged pyramidal lobe –
palpable
• Diagnostics:
• Elevated TSH and presence
of autoantibodies
• FNAB with ultrasound
• Treatment
• Thyroid hormone
replacement if symptomatic
hypothyroid
• Surgery if malignancy is
suspected or if with
significant mass effect

Reidel Thyroiditis
• Rare
• also known as Riedel’s struma
or Invasive Fibrous Thyroiditis
• Thyroid parenchyma is
replaced by fibrous tissue
• Presumed to be autoimmune
• Associated with focal
sclerosing syndromes:
o Mediastinal fibrosis
o Retroperitoneal fibrosis
o Periorbital fibrosis
o Retro-orbital fibrosis
o Sclerosing cholangitis
• Hypothyroid and
hypoparathyroid patient
• Painless thyroid mass that is
hard, woody and fixed to
adjacent tissue
• Weeks to years to produce
symptoms of compression
• Surgery to decompress the
trachea is mainstay of
treatment (wedge excision of
thyroid isthmus)
• Thyroid hormone
replacement

PATHOPHYSIOLOGY
 EPIDEMIOLOGY
 Prevalence of palpable thyroid nodules: 1-5% in those living in
iodine – sufficient areas
 Clinical importance of thyroid nodules rests with the need to
exclude thyroid cancer which occurs in 5-15%
 Thyroid cancer represents about 2% of all new cancer cases and
1% of cancer related deaths in the Philippines
 External-Beam Radiation - risk in developing thyroid carcinoma
(mc: papillary)

 Symptoms
 Hoarseness
 Rapid mass growth
 Change in cosmetic appearance
 Obstructive symptoms: dyspnea and dysphagia
 Physical Examination
 asymptomatic neck mass or cervical lymphadenopathy
 Asses texture, overall size, location and size of nodules and mobility
 Assess voice quality, consider laryngoscopy
 Palpate cervical lymph nodes
 Nodules that are hard, gritty and fixed are more likely malignant

Diagnosis
TOOL REMARKS
Serum TSH Initial test that must be requested in the
evaluation of thyroid nodules
Euthyroid/hypothyroid: FNAB
Hyperthyroid: RAI scan
Thyroid Ultrasound Detecting palpable thyroid nodules
Differentiating solid vs cystic
Identifying cervical lymphadenopathies
Can follow the size of benign thyroid nodules
diagnosed by FNAB
CT Scan Useful for large, fixed, substernal goiters and
evaluation of lung metastases
MRI scan Better than CT for evaluating extrathyroidal tumorr
extension
Done only if with symptoms of extension (e.g
hoarseness, dysphagia, stridor, cough)

DIAGNOSIS
TOOL REMARKS
Iodine Scan Anatomic and physiologic information
Cold lesions: (20% risk of malignancy)
Hot/warm lesions: (<5% risk of malignancy)
Positron Emission Tomogram (PET) Used to screen malignancies when other imaging
are negative
FDG (flurodeoxyglucose) as tracer
Nuclear medicine sudy of choice with cancers
that may not concentrate radioiodine
FNAB Single most important test in the evaluation of
thyroid nodules

Ultrasound of Thyroid
Features suggesting malignancy • Hypoechogenecity
• Microcalcification
• Irregular or blurred nodule margins
• Increased nodular blood flow
visualized by Doppler
• Evidence of tumor invasion or
regional lymph node metastases
Features suggesting malignancy in
Cervical lymph node
• Complex echo pattern or irregular
hyperechoic small intranodular
structures
• Irregular diffuse intranodular blood
flow
• Solbiati index (ratio of largest to
smallest diameter of a node) = 1
• lymph node is more round than
long

Management: Approach to solitary thyroid nodule

BENIGN THYROID NEOPLASMS
PATHOLOGY CLINICAL MANIFESTATIONS MANAGEMENT
Simple Thyroid Cyst
• Lined by epithelial cells
with predominant fluid
component
Ultrasound to rule out any
solid component that will
warrant FNAB
Aspiration up to 3 times
Lobectomy for:
>3 attempts for aspiration
Cysts > 4cm
Complex cysts
Colloid Adenoma
• Uniform appearing
thyroid epithelial cells with
a background of colloid
Nodule is nontender and
soft to rubbery on palpation
If <3 cm: observation
If >3 cm: lobectomy with
isthmusectomy

CLASSIFICATION OF THYROID CANCER
BASED ON HISTOLOGY
Follicullar epithelial cell Differentiated Thyroid Cancer • PAPILLARY CANCER
o Classic morphology
o Encapsulated variant
o Follicular variant
o Aggressive variants (Diffuse
sclerosing variant, Tall cell
variant, Columnar cell
variant)
• FOLLICULAR CANCER
o Classic morphology
(Follicular Carcinoma)
o Hurthle cell variant
Poorly differentiated thyroid
cancer
Insular Carcinoma
Undifferentiated cancer Anaplastic carcinoma
Parafollicular cells or C cell Medullary Thyroid Carcinoma

MALIGNANT NEOPLASMS
OF THE THYROID

PAPILLARY CARCINOMA
• Orphan Annie nuclei
• Psammoma bodies
• Usually multifocal
• Mixed papillary and follicular
tumor behave like their
papillary component
Most common (80%)
F>M, mean age 30-40 yrs
Prior history of external radiation
Commonly have metastases to
cervical lymph nodes
Excellent prognosis (>95%
survival in 10 yrs)
• Near- total or total
thyroidectomy for tumors >
1cm
• Thyroid lobectomy if:
o <1 cm
o Low risk
o No history of irradiation
o No evident metastases
• Neck dissection for
advanced tumors (T3 or T4)

FOLLICULAR CARCINOMA
Usually solitary and
encapsulated
To diagnose, look for vascular
and capsular invasion in surgical
pathology specimen at the time
of surgery
• Common in areas with iodine
deficiency
• F> M, mean age 50 yrs
• Lymph node metastases
uncommon
• 15% mortality in 10 yrs
• FNAB: unable to distinguish
follicular carcinoma from
benign lesions
If diagnosed as follicular tumor
on FNAB: proceed to:
• Thyroid lobectomy: follicular
adenoma
• Total thyroidectomy: if
folicular carcinoma
Prophylactic lymph node
dissection NOT NECESSARY

HURTHLE CELL CARCINOMA
• Arise from oxyphilic cells
• Subtype of follicular throid
CA
• More commonly multifocal
and bilateral
• Metastases to neck nodes
more common
• Higher mortality: 20% in 10 yrs
Same as follicular tumors
Routine central neck node
dissection

MEDULLARY CARCINOMA
• Arise from parafollicular or C
cells in the superolateral
thyroid lobes
• More than half are bilaterl
• Elevated calcitonin or CEA
levels
• May be associated with MEN
2A, MEN2B, familial multiple
thyroid cancer (MTC
syndromes
• CT scan or MRI: to excluse
neck, chest and liver
metastases
Total thyroidectomy with
bilateral central neck
dissection

ANAPLASTIC CARCINOMA
• Giant and multinucleated
cells (spindle cell, squamoid
and pleomorphic giant
cells)
• Might have developed
from follicular or papillary
tumors
• F>M patients in their 60s or
70s
• Highly aggressive tumor
• Lymph node metastases
usually present
• Metastases may be evident
at the time of diagnosis
• Mostly palliative
• Total or near-total
thyroidectomy with
therapeutic neck node
dissection
• En-bloc resection if with
extrathyroidal extension
• Adjuvant radiotheraphy
and chemotheraphy

Classification of Thyroid Cancer based on ability to
concentrate Radioiodine
Usually concentrate radioiodine Differentiated Thyroid Carcinoma (other
than Hurthle, Tall and columnar cell variants)
• Papillary carcinoma: Classic morphology
• Papillary carcinoma: Encapsulated and
follicular variants
• Papillary carcinoma: Diffuse sclerosing
variants
• Follicular Carcinoma other than Hurthle
cell
Frequently DO NOT concentrate radioiodine Tall and Columnar cell variants of Papillary
carcinoma
Hurtle Cell Carcinoma
Poorly differentiated (insular) carcinoma
NEVER concentrate radioiodine Anaplastic Carcinoma
Medullary Carcinoma

FACTORS PREDICTIVE OF HIGH RISK FOR
MALIGNANCY
FACTORS PREDICTIVE OF MODERATE – TO –
LOW RISK
Age <15 or >45 15-45
Sex Male Female
Family History With family history of thyroid cancer No family history
Size >4 cm in diameter <4cm in diameter
Laterality Bilateral Unilateral
Extension Extrathyroidal extension No extrathyroidal extension
Vascular Invasion Present (both papillary and follicular thyroid
cancer)
Absent
Lymph node status Cervical or mediastinal lumph node
metastases
No lymph node metastases
Certain tumor subtypes Hurthle cell
Tall cell
Columnar cell
Diffuse sclerosis
Insular variants
Encapsulated papillary thyroid carcinoma
Papillary microcarcinoma
Cystic papillary thyroid carcinoma
Histology Marked nuclear atypia
Tumor necrosis
Vascular invasion
Absence of nuclear atypia, tumor necrosis
and vascular invasion
Radioiodine Tumors or metastases that concentrate
radioiodine poorly or not at all
Tumors or metastases that concentrate
radioiodine well
Metastases Distant metastases none

Neck Dissection for thyroid cancer
 Elective (prophylactic) dissection of lateral neck compartments (levels II, III or IV) are
not done
 Only indication for compartmental dissection is a clinically positive lymph node
 Jugular lymph nodes (Level II – IV) are dissected in an all or none fashion when one
or more of the compartments contain malignant lymph nodes
 The posterior cervical nodes (Level V) are dissected only when there is a clinically
positive level V nodes or when there is extensive adenopathy in Level II, III or IV
 The superior mediastinal lymph nodes (Level VII) are dissected only when there is a
clinically positive level VII lymph node or when there is extensive adenopathy in
Level IV or VI
 There is almost no indication for a thoracotomy to resect mediastinal adenopathy
 A neck dissection extends the surgical scar up to the side of the neck

Thyroidectomy
 Removal of all or a portion(lobe) of the thyroid gland
 General anesthesia with endotracheal intubation is most often employed
 Indications:
1. Confirmed cancer or suspicion of thyroid nodules
2. Severe reactions to antithyroid medications
3. Large goiters with compressive symptoms
4. Reluctant to undergo RAI

Modes of Thyroidectomy
 Euthyroid prior surgery
 Lugol’s iodine solution: may be given 7-10 days prior to surgery to decrease vascularity
and lessen risk of thyroid storm
MODE Description
Thyroid Lobectomy Removal of all of one thyroid lobe (e.g. that
has a nodule)
May be used for diagnostic purposes as well
Isthmusectomy Resection of the thyroid isthmus only (rarely
done)
Subtotal thyroidectomy Removal of one thyroid lobe, the isthmuss
and part of the second lobe
Total or near total thyroidectomy Removal of all or nearly all of the thyroid
gland (e.d for large goiters, Graves disease)

POSTOPERATIVE MANAGEMENT
OF THYROID CANCER

Radioactive Iodine (131
I, RAI)
• Recommended after Total thyroidectomy in the ff patients to prevent recurrence:
• With known distal metastases
• With tumors > 4cm
• With extrathyroidal extension
• Achieved by either administering an empiric fixed amount of I-131or by using dosimetry-
guided techniques
• Typical doses:
• Low – risk: 30-100 mCi
• High risk: 200 mCi
• Complications include:
• Acute: neck pain, salivary gland swelling, nausea, vomiting
• Long – term: recurrent sialedenitis with dry mouth and taste dysfunction,
hypoparathyroidism, pulmonary fibrosis, bone marrow suppresion, infertility, primary
malignancy elsewhere
• When using radioiodine, it is important to stimulate iodine uptake by elevating serum TSH
levels at least 30U/mL prior to administration

External beam radiotherapy
 Adjuvant treatment to control incompletely resected or recurrent thyroid
carcinoma
 Also used to treat bone metastases and control bone pain

Thyroid Hormone supplementation
 Replacement therapy in patients who underwent near-total or total
thyroidectomy
 Also suppresses TSH, thereby decreasing growth of any residual tumor
 Standard dose is 15 body weight

Level of TSH suppression
 Low risk: at or below 0.1-0.5 mU/L
 High risk: less than 0.1 mU/L

Potential Complications of Thyroid Cancer Surgery
STRUCTURE INJURED INCIDENCE OF SYMPTOMATIC PROBLEM
Recurrent Laryngeal Nerve Hoarseness
Temporary: 30%
Permanent: 2%
Parathyroid Glands Hypoparathyroidism
Temporary: 5%
Permanent: 0.5%
Spinal accessory nerve Shoulder weakness +/- pain
Only with Level II/V dissection
Rare with negative Level II or V nodes
Temporary: 50%
Permanent: 25%
Superior Laryngeal Nerve Change in voice capability
Usually symptomatic only in professional voice users
Vagus Nerve Permanent Hoarseness: 0.5% (higher with
extrathyroidal tumor extension)
Trachea, esophagus, carotid artery Rare in the absence of extensive invasion by tumor
Thoracic duct Rare in the absence of dissection of level IV, VI or VII

Gross Anatomy
 4 Parathyroid glands
 Ovoid shape measuring 7 mm
 Weighs 40 – 50 mg
 Superior glands
 more consistent in position
 Dorsal to the recurrent laryngeal nerve at the level of the cricoid
cartilage
 Inferior glands
 More variable in position
 Most common position is within a distance of 1 cm from a point
centered where inferior thyroid artery and RLN cross
 Ventral to the recurrent laryngeal nerve

Gross anatomy
 Blood supply
 Superior and inferior thyroid arteries
 Histology
 PTH produced by chief cells
 Small amount of PTH secreted by oxyphil cells and water – clear
cells
 Physiology
 Effects of PTH: inc calcium, dec phosphate
 Increase bone resorption
 Decrease excretion of calcium
 Decrease reabsorption of phosphate in the kidneys

GENERAL DISORDERS OF THE
PARATHYROID GLAND

PRIMARY HYPERPARATHYROIDISM
• Increased PTH from abnormal
parathyroid glands, exact
etiology unknown
• Familial cases occur in MEN I,
MEN2A syndromes
• Results from enlargement of a
single gland or parathyroid
adenima (80%), multiple
adenomas or hyperplasia (15-
20%) and parathyroid
carcinoma (1%)
Classic Pentad:
• Kidney stones
• Painful bones
• Abdominal groans
• Psychic moans
• Fatigue overtones
Symptomatic patients:
parathyroidectomy
Asymptomatic, surgery
recommended when:
• Serum Ca2+
>1mg/dL above
upper limits of normal
• GFR <60 mL/min
• >2.5 SD below peak bone
mass, T score < -2.5 on bone
densitometry
• Age < 50 years
• Medical surveillance not
possible or desired by patient

SECONDARY HYPERPARATHYROIDISM
• Increased PTH in respinse to
hypocalcemic states
(chronic renal failure,
inadequate calcium
intake, gut malabsorption)
• Calciphylaxis: painful
violaceous lesions on the
extremoties that may
necrose and become
gangrenous, leading to
sepsis and death
• Medical: cinacalcet
(calcimimetic)
• Parathyroidectomy: if PTH
remains high despite
medical therapy

TERTIARY HYPERPARATHYROIDISM
PATHOPHYSIOLOGY CLINICAL
MANIFESTATIONS
MANAGEMENT
• Autonomously functioning
parathyroid glands after
correction of underlying
disorder in secondary
hyperparathyroidism (e.g.
after renal transplantation)
• Similar to primary
hyperparathyroidism
Medical: cinacalcet
(calcimimetic)
Parathyroidectomy: if
symptomatic or if with
persistence of elevated PTH>1
year after kidney transplantation

HYPOPARATHYROIDISM
Most common is thyroid surgery
DiGeorge syndrome:
congenital absence of
parathyroid glands
Hypocalcemia usually transient
Tingling sensation on the
fingertips and around the lips
Chvostek’s sign: tapping on the
facial nerve anterior to the ear
causes contraction of ipsilateral
facial muscles
Trosseau sign: carpopedal
spasm after occlusion of blood
flow to the forearm
Tetany (worst case)
Medical: calcium and vitamin
D supplementation

NEOPLASMS OF THE
PARATHYROID GLANDS

Pathophysiology
Parathyroid neoplasms are rare endocrine tumors
with an estimated incidence of 0.015 in 100,000
population
Risk factors:
Family history of multiple endocrine neoplasia Type I or II
Exposure to external radiation

 Parathyroid Adenoma and hyperplasia: usually presents with asymptomatic
hypercalcemia
 Parathyroid Carcinoma: manifests with severe hypercalcemia
 (mental status changes, fatigue, bone pain, abdominal pain and kidney
stone formation due to primary hyperparathyroidism)

Diagnosis
TOOLS FINDINGS OR REMARKS
Parathyroid hormone (PTH) and serum
calcium levels
Hallmark of primary hyperparathyroidism:
elevated PTH and serum calcium
Sestamibi scan Uses a radioisotope taken by the parathyroid
glands to show activity
Also useful for detecting extopic parathyroids
Ultrasound Complementary imaging study providing
anatomic information for operative planning

Management
CONDITION MANAGEMENT
Parathyroid Adenoma Single gland parathyroidectomy following four-
gland exploration
Parathyroid Hyperplasia 3.5 Parathyroidectomy or total
parathyroidectomy with autotransplantation
Parathyroid carcinoma Tumor is removed en bloc along with the
thyroid lobe, the cervical thymus and the
contents of the central compartment
If the recurrent laryngeal nerve is involved, it
should be resected with the specimen
Adjuvant radiotherapy for high risk patients
Hypercalcemic crisis Mainstay in management: intravenous
hydration with saline
IV mitramycin, calcitonin, steroids,
bisphosphonates
Hemodialysis

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