Thyroid Neoplasm
last authored: April 2012, David LaPierre
last reviewed:
Introduction
Papillary carcinoma is the most common type of thyroid cancer and is showing the sharpest ↑ in incidence of all carcinomas in Canada. Its peak incidence is 30-40 years.
Cancer types, with worsening prognosis
- pretty
- follicular
- hurthle
- medullary
- anaplastic
"Pretty females have men always"
Follicular carcinoma accounts for 15-20% of thyroid cancers, and is most common in people 40-50 years old. It is most prevalent in iodine-deficient areas.
Medullary carcinoma, occurring in 5-10% of thyroid malignancies, originates in parafollicular ‘C’ cells. Eighty percent are sporadic and the rest are familial (including MEN type II).
Causes and Risk Factors
Risk factors of malignancy in investigating a thyroid nodule include:
- head and neck irradiation
- family history
- young age
- male sex
- rapid growth
Pathophysiology
Signs and Symptoms
Typical presentation of Ca: asymptomatic thyroid nodule in euthyroid patient
- history
- physical exam
History
Cancer can often be asymptomatic. However, symptoms can incude:
- pain
- dysphagia
- hoarseness
Physical Exam
The thyroid exam may show the following ominous signs:
- hard consistency of the nodule
- fixation of nodule to underlying tissues
- lymphadenopathy
Investigations
- lab investigations
- diagnostic imaging
Lab Investigations
Investigations of a thyroid nodule begin with
- TSH
- T4 +/- T3
A fine needle aspiration (FNA) biopsy is a key step in diagnosis.
- papillary: readily diagnosed
- follicular: no cytologic diagnosis possible - need capsular or vascular invasion on resected specimen.
Elevated calcitonin levels may be present with medullary carcinoma.
Diagnostic Imaging
Ultrasound is one of the first imaging modalities.
Radiouptake scan: a cold gland suggests malignancy/
Treatments
Papillary carcinoma is treated by total thyroidectomy if a history of radiation is present, or thyroid lobectomy if not. Nodal excision is required if spread is detected.
, central LN dissection (level VI) + I-131.
Surveillance: serum thyroglobulin ± iodine scan
Consequences and Course
Papillary
Less than 5% of papillary cancers have metastasized at time of presentation.
Follicular
Rare LN mets: spreads hematogenously (lung, liver)
Medullary carcinoma is an aggressive form, with early LN mets. Rx: Total thyroidectomy + LN dissection + Radiation (external beam RT, not I-131). Surveillance: serum calcitonin.
Undifferentiated cancer has usually spread at time of presentation.
Risks for thyroid surgery include:
- vocal cord weakness
- hypocalcemia
- hematoma with airway obstruction
Additional Resources
Topic Development
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