Follicular Thyroid Cancer

Abstract Follicular thyroid cancer (FTC) is the second most common histologic subtype of differentiated thyroid cancer behind papillary thyroid cancer (PTC). The rate of FTC diagnosis is declining over time due to changes in the diagnostic criteria and to environmental factors such as iodine sufficiency. The diagnosis is challenging because FTCs are distinguished from follicular thyroid adenomas (FTAs) solely by the presence of capsular and/or vascular invasion, neither of which can be assessed in cytology specimens. FTC spreads through blood vessels, and lymph node metastases are rarer (