KEY FACTS
Terminology
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Well-defined histology: Papillary and follicular carcinoma
Imaging
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Papillary carcinoma (~ 80% of thyroid cancer)
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Majority are ill-defined with irregular outlines
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10-20% multifocal, 70% solid; 77-90% hypoechoic
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Calcifications: Punctate small echogenic foci highly specific; larger calcifications also concerning
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Cystic variant: Rare, eccentric polypoid solid vascular nodule within cyst ± microcalcifications
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Nodes predominantly hyperechoic (80%) compared to muscles; 50% with punctate microcalcification; cystic change in 25%
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Follicular carcinoma (~ 10% of thyroid cancer)
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Ill-defined solid tumor; hypoechoic, heterogeneous
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Large tumors invade strap muscles, esophagus, trachea, recurrent laryngeal nerve, neck vessels
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Color Doppler: Profuse chaotic vascularity within nodule or in wall, and septa of partially cystic tumors
Top Differential Diagnoses
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Multinodular goiter
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Thyroid adenoma
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Aggressive thyroid carcinomas and metastases
Clinical Issues
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Painless, palpable thyroid nodule or incidental finding on imaging
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Rapid growth of thyroid mass, extrathyroidal hard nodes, hoarseness; history of radiation exposure
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Low mortality from malignancy; 20-year survival rate: 90% papillary, 75% follicular
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Peak incidence in 3rd and 4th decade; F:M = 3:1
Scanning Tips
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Look for extrathyroidal extension by evaluating capsule and mobility during swallowing; evaluate nodal chains
is taller than it is wide, with lobulated margins, and hypoechoic relative to normal thyroid 
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shows color flow in the center of the tumor.
is markedly hypoechoic relative to normal thyroid 
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is poorly marginated and is hypoechoic in comparison to the thyroid with multiple echogenic foci.
with a thin calcified incomplete rim. There are numerous small punctate echogenic foci 
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