Download Thyroid Nodules and Thyroid Cancer

Thyroid Nodules and Thyroid
Cancer
Dr. Boyd Lee
Otolaryngology – Head and Neck
Surgery
Memorial University
Anatomy
Anatomy
• 2 lateral lobes
connected by isthmus
• Pyramidal lobe 50%
• Isthmus lies over 2nd –
3rd tracheal ring
Anatomy
• Blood supply
– Superior and Inferior
thyroid a.
– Superior, middle, and
inferior thyroid v.
Anatomy
• Lymphatic drainage
– Prelaryngeal (delphian)
node
– Pretracheal nodes
– Paratracheal nodes
– Lateral neck nodes
Thyroid Lymphatics
Anatomy
• Innervation
– Parasympathetic via
vagus
– Sympathetic via
cervical sympathetic
chain
Anatomy
• Recurrent Laryngeal
nerves
– Lie in Tracheoesophageal
grooves adjacent to thyroid
– Branches of Vagus n.
– Left loops around aortic
arch
– Right loops around right
subclavian a.
– Innervates intrinsic muscles
of larynx except
cricothyroid m.
Anatomy
• Parathyroid glands
– Paired superior and
inferior parathyroid
glands on posterior
aspect of thyroid
within thyroid capsule
Physiology
• Endocrine gland
• Follicular cells
produce T4 and T3
• Parafollicular cells (C
cells) produce
calcitonin
Thyroid Disorders
• Disorders of function
– Hypothyroidism
– Hyperthyroidism
– Autoimmune
• Disorders of anatomy
– Thyroid nodules
• Cysts
• Adenomas
• Carcinomas
– Goiter
Thyroid Nodules
• “Discrete lesion within the thyroid gland
that is radiologically distinct from the
surrounding thyroid parenchyma.”
• Not all palpable lesions correspond to a
radiologically distinct abnormality
• Presence of a nodule(s) in the thyroid does
not necessarily affect function of the gland
Thyroid Nodule
Thyroid Nodules
• Palpable thyroid nodules
– 5% of women
– 1% of males
• US detected nodules
– 19-67% randomly selected individuals
– Higher incidence in women and the elderly
• Generally, only nodules >1 cm need to be
investigated unless other factors or SSx present
Thyroid Nodules
• Only 6% of 1 cm nodules
are palpable
• Only 50% of 1-2cm
nodules are palpable
• Even 50-60% of >2 cm
nodules are not detected
clinically
• Non-palpable nodules
carry same risk of
malignancy as palpable
nodules
• Factors affecting the
palpability of nodules
– Size of nodule
– Thickness of neck
– Position of the nodule
(posterior, inferior,
retro-sternal)
– Experience of the
examiner
Thyroid Nodules
• 5-15% of thyroid nodules are malignant
• Depends on:
–
–
–
–
Age
Sex
Radiation exposure
Family history
Thyroid Cancer
• Well Differentiated
– Papillary (85%)
– Follicular (5%)
• Poorly Differentiated
– Medullary (5%)
– Anaplastic
• Other
– Lymphoma
– Sarcoma
– Metastases
Thyroid Cancer
• Thyroid Cancer is one of 2 cancers that has an
increasing incidence
• 3.6/100 000 in 1973
• 8.7/100 000 in 2002
• Increase is almost entirely due to papillary thyroid
ca (PTC)
• Increase may be partly due to better detection
• May also be secondary to increased radiation
esposure
Thyroid Nodule Workup
• Thorough History and Physical
Thyroid Nodule Workup
• History
– Childhood neck radiation or
ionizing radiation exposure
from fallout in childhood
– Total body irradiation for
BMT or Hodgkins
– FHx of Thyroid Ca, MEN,
Cowden, Gardner, or
Werner syndromes.
– Rapid growth
– Hoarseness
• Physical
–
–
–
–
Fixation of nodule
Vocal cord paralysis
Cervical adenopathy
> 1 cm
Thyroid Nodule Workup
• Thyroid Function studies
– Serum TSH
– If TSH is subnormal nuclear medicine scan is
ordered
– No further workup necessary if the nodule is
hyperfunctioning (ie hot)
Thyroid Nodule Workup
• Diagnostic Imaging
– Thyroid US should be performed in all patients
with known or suspected thyroid nodules
Thyroid Nodule Workup
• US findings
suggesting a benign
nodule
– Purely cystic
– Spongiform nodule
• US findings suggesting a
malignant nodule
– Hypoechogenicity
– Increased intranodular
vascularity
– Irregular infiltrative
margins
– Microcalcifications
– Absent halo
– Shape taller than width in
transverse dimension
Thyroid US
Spongiform Nodule
Thyroid Cyst
Mixed Cyst
Papillary Ca
Papillary Ca
Fine Needle Aspiration Bx
• FNA is the most
accurate and cost
effective method for
evaluating thyroid
nodules.
• US guidance increases
sensitivity and
specificity of the FNA
Thyroid FNA
FNA Results
•
•
•
•
•
Benign (5% risk of cancer)
Suspicious for Cancer (85% risk of Ca)
Cancer (95% risk of Ca)
Follicular Lesion
Atypical lesion of uncertain significance (515% risk of Ca)
• Non-diagnostic
Indications for Thyroid Surgery
• Cancer (Papillary, Follicular, Medullary)
• Suspicion for, or risk of Cancer
• Compressive Sx
– Dyspnea
– Dysphagia
• Hyperthyroidism
• Cosmesis
Pre-op/ Post-op Assessment
• Flexible laryngoscopy
• US of lateral neck if Papillary Ca to
determine presence of lymphadenopathy +
FNA Bx of any suspicious nodes
Papillary Thyroid Ca
•
•
•
•
•
•
Females > males
Increased risk from radiation
Can be multi-focal
Lymphatic spread
Role of 131I treatment post -op
Excellent prognosis
– 97% 5 yr survival
– 93% 10 yr survival
– Prognosis better in age < 45, females
Follicular Thyroid Ca
•
•
•
•
•
Cannot Dx on FNA
Dx made on vascular or capsular invasion
Hematogenous spread to lungs, bone
Role of 131I treatment post -op
Very good prognosis
– 91% 5 yr survival
– 85% 10 yr survival
Medullary Thyroid Ca
•
•
•
•
•
•
•
•
Arises from C cells
25% of cases are genetic (MEN 2)
RET proto-oncogene
Calcitonin and CEA are makers
Presents with flushing/diarrhea
No role for 131I post op
80% 5 yr survival
75% 10 yr survival
Anaplastic Thyroid Ca
• Poorly differentiated
• Highly aggressive
• Can be difficult to distinguish from
thyroidal lymphoma
• Surgical therapy includes open biopsy &
palliative tracheostomy
• External beam radiation
• Very poor prognosis
The Future of Thyroid Surgery
Summary
• Thyroid nodules are very common
• Can be hard to palpate
• More commonly diagnosed due to imaging
for other reasons (incedentalomas)
• Thyroid cancer is increasing
• Overall good prognosis compared with
other cancers