A thyroid nodule is a growth or lump that forms within the thyroid gland.
It is discovered either by palpation or incidentally noted on a radiologic procedure, such as carotid ultrasonography, neck or chest computed tomography [CT], or positron emission tomography [PET]).
Their clinical importance is primarily related to the need to exclude thyroid cancer, which accounts for 4 to 6.5 percent of all thyroid nodules in nonsurgical series.1
Reference
1. Werk EE Jr, Vernon BM, Gonzalez JJ, Ungaro PC, McCoy RC Cancer in thyroid nodules. A community hospital survey. Arch Intern Med. 1984;144(3):474.