Thyroid Nodules and Thyroid Cancer - Faculty of Medicine
Transcript of Thyroid Nodules and Thyroid Cancer - Faculty of Medicine
Thyroid Nodules and Thyroid Cancer
Dr. Boyd Lee Otolaryngology – Head and Neck
Surgery Memorial University
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
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
• 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
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
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 (5-
15% 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
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