Thyroid Nodule

Excerpt

The American Thyroid Association (ATA) defines the thyroid nodule as a discrete lesion within the thyroid gland. It is radiologically distinct from the surrounding thyroid parenchyma. Nodules may be solitary, multiple, cystic, or solid.

Nodules in the thyroid gland are a common entity and are detected in approximately 5% to 7% of the adult population by physical examination alone. However, autopsy data have shown a 50% prevalence of thyroid nodules larger than one centimeter in patients without previously diagnosed thyroid disease. Nodules are found with increasing frequency, likely due to the widespread use of modern imaging modalities, particularly ultrasound (US), but also computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET).

Although more than 90% of detected nodules are clinically insignificant benign lesions, thyroid nodules are clinically important as they may represent thyroid cancer in approximately 4.0% to 6.5% of cases.