A thyroid nodule is a discrete lesion distinct from the surrounding thyroid parenchyma. Enlargement of other nearby anatomic structures, such as the parathyroid glands or regional lymph nodes, as well as branchial cleft and thyroglossal duct cysts, may sometimes be confused with thyroid nodules.
Thyroid nodules are a common clinical problem.[1]Haugen BR, Alexander EK, Bible KC, et al. 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2016 Jan;26(1):1-133.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4739132
http://www.ncbi.nlm.nih.gov/pubmed/26462967?tool=bestpractice.com
They can be found in 50% to 60% of healthy people.[2]Gharib H, Papini E, Garber JR, et al. AMERICAN ASSOCIATION OF CLINICAL ENDOCRINOLOGISTS, AMERICAN COLLEGE OF ENDOCRINOLOGY, AND ASSOCIAZIONE MEDICI ENDOCRINOLOGI medical guidelines for clinical practice for the diagnosis and management of thyroid nodules - 2016 update. Endocr Pract. 2016 May;22(5):622-39.
https://www.endocrinepractice.org/article/S1530-891X(20)42954-4/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/27167915?tool=bestpractice.com
Most thyroid nodules are asymptomatic and are detected by palpation or incidentally detected during an imaging procedure.[3]Alexander EK, Cibas ES. Diagnosis of thyroid nodules. Lancet Diabetes Endocrinol. 2022 Jul;10(7):533-9.
http://www.ncbi.nlm.nih.gov/pubmed/35752200?tool=bestpractice.com
In an international retrospective analysis of patients who underwent thyroid-directed surgery, radiologic procedures performed for other indications detected thyroid nodules in 20% of cases.[4]Sajisevi M, Caulley L, Eskander A, et al. Evaluating the rising incidence of thyroid cancer and thyroid nodule detection modes: a multinational, multi-institutional analysis. JAMA Otolaryngol Head Neck Surg. 2022 Sep 1;148(9):811-8.
https://jamanetwork.com/journals/jamaotolaryngology/fullarticle/2794184
http://www.ncbi.nlm.nih.gov/pubmed/35834240?tool=bestpractice.com
Incidental detection of thyroid nodules is thought to be behind an increased reported incidence of thyroid cancers globally.[5]La Vecchia C, Malvezzi M, Bosetti C, et al. Thyroid cancer mortality and incidence: a global overview. Int J Cancer. 2015 May 1;136(9):2187-95.
https://onlinelibrary.wiley.com/doi/10.1002/ijc.29251
http://www.ncbi.nlm.nih.gov/pubmed/25284703?tool=bestpractice.com
Thyroid nodules are more common in female patients.[1]Haugen BR, Alexander EK, Bible KC, et al. 2015 American Thyroid Association management guidelines for adult patients with thyroid nodules and differentiated thyroid cancer. Thyroid. 2016 Jan;26(1):1-133.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4739132
http://www.ncbi.nlm.nih.gov/pubmed/26462967?tool=bestpractice.com
[4]Sajisevi M, Caulley L, Eskander A, et al. Evaluating the rising incidence of thyroid cancer and thyroid nodule detection modes: a multinational, multi-institutional analysis. JAMA Otolaryngol Head Neck Surg. 2022 Sep 1;148(9):811-8.
https://jamanetwork.com/journals/jamaotolaryngology/fullarticle/2794184
http://www.ncbi.nlm.nih.gov/pubmed/35834240?tool=bestpractice.com
The prevalence of thyroid nodular disease increases with advancing age.[6]Kwong N, Medici M, Angell TE, et al. The influence of patient age on thyroid nodule formation, multinodularity, and thyroid cancer risk. J Clin Endocrinol Metab. 2015 Dec;100(12):4434-40.
https://academic.oup.com/jcem/article/100/12/4434/2536300
http://www.ncbi.nlm.nih.gov/pubmed/26465395?tool=bestpractice.com
Despite this increase in nodularity, thyroid nodules in older adults have a lower risk of malignancy; however, when thyroid cancer is identified, it is more likely to be of high-risk histology.[6]Kwong N, Medici M, Angell TE, et al. The influence of patient age on thyroid nodule formation, multinodularity, and thyroid cancer risk. J Clin Endocrinol Metab. 2015 Dec;100(12):4434-40.
https://academic.oup.com/jcem/article/100/12/4434/2536300
http://www.ncbi.nlm.nih.gov/pubmed/26465395?tool=bestpractice.com
[7]Ospina NS, Papaleontiou M. Thyroid nodule evaluation and management in older adults: a review of practical considerations for clinical endocrinologists. Endocr Pract. 2021 Mar;27(3):261-8.
http://www.ncbi.nlm.nih.gov/pubmed/33588062?tool=bestpractice.com
Autopsy studies detect nodules in over half of the general population by the fifth or sixth decades of life.[8]MORTENSEN JD, WOOLNER LB, BENNETT WA. Gross and microscopic findings in clinically normal thyroid glands. J Clin Endocrinol Metab. 1955 Oct;15(10):1270-80.
http://www.ncbi.nlm.nih.gov/pubmed/13263417?tool=bestpractice.com
Most nodules are benign.[9]Singh Ospina N, Iñiguez-Ariza NM, Castro MR. Thyroid nodules: diagnostic evaluation based on thyroid cancer risk assessment. BMJ. 2020 Jan 7;368:l6670.
http://www.ncbi.nlm.nih.gov/pubmed/31911452?tool=bestpractice.com
The risk of thyroid cancer in any patient presenting for nodule care is approximately 7% to 15%.[3]Alexander EK, Cibas ES. Diagnosis of thyroid nodules. Lancet Diabetes Endocrinol. 2022 Jul;10(7):533-9.
http://www.ncbi.nlm.nih.gov/pubmed/35752200?tool=bestpractice.com
The clinical goal in the evaluation of the thyroid nodule is differentiating a benign from a malignant lesion.
