Indeterminate Thyroid Cytology and Impact of Noninvasive Follicular Thyroid Neoplasm with Papillary-like Features on Preoperative Diagnosis

Abstract

Abstract Since the introduction of “noninvasive follicular thyroid neoplasm with papillary-like features” terminology, there has been much discussion and debate on how to best accommodate this new classification and its anticipated effect on cytologic preoperative risk of malignancy. Noninvasive follicular thyroid neoplasm with papillary-like features is a recently proposed terminology that was applied to a subset of noninvasive follicular variant of papillary thyroid carcinomas to avoid the label of “cancer.” In this review, the impact of noninvasive follicular thyroid neoplasm with papillary-like features on thyroid FNA diagnosis and risk of malignancy is discussed, as well as its impact on the 2017 updates to the Thyroid Bethesda system classification. Minimal cytologic criteria for establishing a definitive diagnosis of papillary thyroid carcinoma are discussed, as well as detailed diagnostic criteria of the indeterminate thyroid categories, which include atypia/follicular lesion of undetermined significance, follicular neoplasm/suspicious for follicular neoplasm, and suspicious for malignancy. The role of molecular testing in management is briefly visited.