Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features: Historical Context, Diagnosis, and Future Challenges.

The encapsulated/well-demarcated non-invasive form of follicular variant of papillary thyroid carcinoma (FVPTC) that occurs annually in 45,000 patients worldwide was thought for 30 years to be a carcinoma. Many studies have now shown almost no recurrence in these non-invasive tumors, even in patients treated by surgery without radioactive iodine therapy. The categorization of the tumor as cancer has led to aggressive forms of treatment, with their side effects, financial costs, and the psychological and social impact of a cancer diagnosis. Recently, the encapsulated/well-demarcated non-invasive, FVPTC was renamed as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) by an international group of experts. The new terminology lacks the carcinoma label enabling clinicians to avoid aggressive therapy. By taking the reader through the history of FVPTC, this article explains how diagnostic criteria for thyroid carcinoma of follicular cells have evolved over the last 60 years. It discusses the steps that led to the labeling of FVPTC as cancer and highlights the various studies that helped reclassify and rename this tumor. It also sheds light on the impact of this reclassification on cytologic diagnosis and focuses on the studies needed to refine and expand the histologic criteria of NIFTP. By understanding the history of this change in nomenclature, future classification of tumors will be greatly improved.