_________________________________________________________________________ Thyroid Dysfunction
While imaging studies are no longer routinely used as part of the initial diagnostic evaluation of solitary thyroid nodules, nuclear imaging can be used to describe thyroid nodules as “hot” or “cold.” Hot nodules are functional and produce thy- roid hormone; they are almost never cancerous. A cold nodule is nonfunctional or inactive, producing little or no thyroid hormone. These nodules are malignant in approximately 5% to 8% of patients [31]. Ultrasound is highly sensitive in deter- mining the size and number of thyroid nodules; however, it cannot reliably be used alone to distinguish between a benign and a malignant nodule. It may be helpful in some cases when it is used to guide fine-needle aspiration biopsy [31] . An open biopsy or a fine-needle aspiration biopsy is an important step in determining the type of nodule. Fine-needle aspiration biopsy has been demonstrated to be highly accurate (i.e., mean sensitivity greater than 80% and mean specificity greater than 90%). Routine use of fine-needle aspiration biopsy in diagnostic evaluation can reduce the need for diagnostic thyroidectomy by 20% to 50% [31] . In 2010, to improve the clarity and consistency of thyroid cyto- pathology, the National Cancer Institute released the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC). The TBSRTC has since been updated in 2017 and 2023 to continue to unify terminology and eliminate duplication in diagnostic nomenclature. One focus of the 2023 TBSRTC was aligning with the updated 2022 World Health Organization Clas- sification. The diagnostic categories, examples of diagnostic entities, risk of malignancy, and recommended management are detailed in Table 1 [32] . As noted, treatment may or may not be necessary. Nodules that appear benign may simply be watched for changes. Levo- thyroxine may be prescribed on the theory that it may induce a reduction in the size of the nodule and/or prevent further nodule development. If cancer is suspected, surgical removal is usually recommended [24; 31; 32] .
THYROID NODULES Nodules in or on the thyroid gland are fairly common, and are 10 times more common in older adults than in young people and are more common in women than men. The estimated lifetime risk for developing thyroid nodules is 5% to 10% , and the majority of nodules will turn out to be benign, with only 7% to 15% being malignant nodules; even malignant cases are curable 95% of the time [7; 31] . Most nodules are initially found when the neck is palpated during a routine physical examination. Individuals may also notice a vague sensation of pressure in the neck or discomfort when swallowing. It is important to note that during physi- cal exams, thyroid nodules are only palpable in about 5% of women and 1% of men, but a newer diagnostic method using high-resolution ultrasound can detect nodules in 19% to 68% of individuals [31] Some nodules are simply an overgrowth of normal thyroid tis- sue. Other causes include inflammation (as with thyroiditis), fluid-filled cysts, or benign or cancerous tumors. Nodules are generally classified as [24; 31]: • Colloid nodule: a benign overgrowth of normal thyroid tissue • Follicular adenoma: a benign nodule similar in appearance to follicular cancer • Thyroid cyst: usually benign if all fluid filled, but can be cancerous if complex or mixed with solid components • Inflammatory nodule: develops as the result of chronic inflammation and can cause severe pain • Thyroid cancer • Multinodular goiter
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Book Code: ANCCTX2027
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