The History of the Follicular Variant of Papillary Thyroid Carcinoma

Context: This review provides historical context to recent developments in the classification of the follicular variant of papillary thyroid carcinoma (FVPTC). The evolution of the diagnostic criteria for papillary thyroid carcinoma is described, clarifying the role of molecular analysis and the impact on patient management. Methods: A PubMed search using the terms "follicular variant" and "papillary thyroid carcinoma" covering the years 1960 to 2016 was performed. Additional references were identified through review of the citations of the retrieved articles. Results: The encapsulated/well-demarcated, noninvasive form of FVPTC that occurs annually in 45,000 patients worldwide was thought for 30 years to be a carcinoma. Many studies have shown almost no recurrence in these noninvasive tumors, even in patients treated by surgery alone without radioactive iodine therapy. The categorization of the tumor as outright cancer has led to aggressive forms of treatment, with their side effects, financial costs, and the psychological and social impacts of a cancer diagnosis. Recently, the encapsulated/well-demarcated, noninvasive FVPTC was renamed as noninvasive follicular thyroid neoplasm with papillary-like nuclear features. The new terminology lacks the carcinoma label, enabling clinicians to avoid aggressive therapy. Conclusions: By understanding the history of FVPTC, future classification of tumors will be greatly improved.