J Pathol Transl Med.  2022 Nov;56(6):319-325. 10.4132/jptm.2022.09.29.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features: its updated diagnostic criteria, preoperative cytologic diagnoses and impact on the risk of malignancy

• Na HY
• Park SY

• KMID: 2535851
• DOI: http://doi.org/10.4132/jptm.2022.09.29

Abstract

Due to the extremely indolent behavior, a subset of noninvasive encapsulated follicular variant papillary thyroid carcinomas has been classified as “noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP)” since 2016 and is no longer considered carcinoma. Since the introduction of this new terminology, changes and refinements have been made in diagnostic criteria. Initially, the incidence of NIFTP was estimated substantial. However, the reported incidence of NIFTP varies greatly among studies and regions, with higher incidence in North American and European countries than in Asian countries. Thus, the changes in the risk of malignancy (ROM) in the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) differ inevitably among regions. Because more conservative surgery is recommended for NIFTPs, distinguishing NIFTPs from papillary thyroid carcinomas in preoperative fine-needle aspiration cytology became one of the major concerns. This review will provide comprehensive overview of updates on diagnostic criteria, actual incidence and preoperative cytologic diagnoses of NIFTP, and its impact on the ROM in TBSRTC.

Keyword

Thyroid; Noninvasive follicular thyroid neoplasm with papillary-like nuclear features; Fine-needle aspiration cytology; Risk of malignancy

Figure

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  Fig. 1. Histologic and cytologic features of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). (A) A well-demarcated mass composed of variable-sized neoplastic follicles is observed in scan view. (B) In high power view, mild nuclear atypia including chromatin clearing, and occasional nuclear grooves which corresponds to “nuclear score 2” is seen (B). (C, D) Fine-needle aspiration cytology of NIFTP generally shows syncytial cell clusters containing microfollicles. Thick colloid can be observed in the microfollicles (arrows). (E, F) Pale chromatin, occasional nuclear grooves, marginal nucleoli are seen. The nuclear atypia is typically mild and patchy. Intranuclear pseudoinclusions, psammomatous calcifications are absent in the presented cases.

Reference

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