Previously undiagnosed thyroid lesions discovered on imaging studies conducted for other reasons.
Discovered with ultrasound, CT scan, MRI and PET scan.
Risk of malignancy 1.5-10% of incidentalomas found on ultrasound.
Review of 4,525 PET scans for staging malignancy revealed 2.3% of thyroid incidentalomas, with about 50% of these lesions being thyroid cancers (Cohen).