Thyroid Neoplasm
last authored: Sept 2009, 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.
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).
Risks for thyroid surgery: vocal cord weakness, hypocalcemia, hematoma with airway obstruction
Causes and Risk Factors
Risk Factors: Family History, Radiation
Pathophysiology
Signs and Symptoms
Typical presentation of Ca: asymptomatic thyroid nodule in euthyroid patient
- history
- physical exam
History
Physical Exam
Investigations
Workup: U/S & FNA biopsy
PCT: readily diagnosed on FNA. early mets to LNs.
Follicular carcinoma: no cytologic diagnosis possible - need capsular or vascular invasion on resected specimen. Rare LN mets: spreads hematogenously (lung, liver)
- lab investigations
- diagnostic imaging
Lab Investigations
Diagnostic Imaging
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
Less than 5% of papillary cancers have metastasized at time of presentation.
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.
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