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 2,3. The incidence is estimated at 0.1% with a lifetime prevalence of 10% 3.
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 1-3. 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 3.
Thyroid nodules are typically benign. The prevalence of malignancy (based on biopsy) in thyroid nodules is ~10% (range 4-6-15%) 3,4.
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.
- 1. Arun C. Nachiappan, Zeyad A. Metwalli, Brian S. Hailey, Rishi A. Patel, Mary L. Ostrowski, David M. Wynne. The Thyroid: Review of Imaging Features and Biopsy Techniques with Radiologic-Pathologic Correlation. (2014) RadioGraphics. 34 (2): 276-93. doi:10.1148/rg.342135067 - Pubmed
- 2. Xie C, Cox P, Taylor N, LaPorte S. Ultrasonography of thyroid nodules: a pictorial review. (2016) Insights into imaging. 7 (1): 77-86. doi:10.1007/s13244-015-0446-5 - Pubmed
- 3. Popoveniuc G, Jonklaas J. Thyroid nodules. (2012) The Medical clinics of North America. 96 (2): 329-49. doi:10.1016/j.mcna.2012.02.002 - Pubmed
- 4. Haugen et al. 2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer: The American Thyroid Association Guidelines Task Force on Thyroid Nodules and Differentiated Thyroid Cancer. (2016) Thyroid. 26 (1): 1-133. doi:10.1089/thy.2015.0020 - Pubmed
- 5. Pacini F, De Groot LJ. Thyroid Nodules. [Updated 2016 Jul 1]. In: Feingold KR, Anawalt B, Boyce A, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK285543/
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