Thyroid nodules are any discrete lesion that can be delineated on imaging studies from the adjacent thyroid parenchyma. They can represent a range of benign or malignant conditions.
They are more common in females (4:1 F: M) and have an increasing prevalence with increasing age and reduced iodine intake . The incidence is estimated at 0.1% with a lifetime prevalence of 10% .
Thyroid nodules are a common incidental finding on imaging (see: incidental thyroid nodules), present in ~10% of CT and MRI neck examinations, ~50% (range 20-76%) of ultrasound neck ultrasound, and 55% (range 50-65%) of autopsies . They can also be found on clinical examination as palpable lesions in the neck, although this clinical finding does not represent a thyroid nodule if there is no imaging correlate.
When symptomatic, patients may present with thyroid dysfunction or rarely compressive symptoms .
Thyroid nodules are typically benign. The prevalence of malignancy (based on biopsy) in thyroid nodules is ~10% (range 4-6-15%) .
There are many causes of thyroid nodules, some of the more common causes are listed below:
- benign nodules
- malignant nodules
Treatment and prognosis
As thyroid nodules are commonly incidental, there are numerous classification systems to help with risk stratification. See article: Incidental thyroid nodules for further detail.