Change in Diagnostic Criteria for Noninvasive Follicular Thyroid Neoplasm With Papillarylike Nuclear Features

Abstract

, proposed reclassification of a type of lowrisk thyroid cancer as noninvasive follicular thyroid neoplasm with papillarylike nuclear features (NIFTP), eliminating the term cancer from the tumor name. 1 Since then, the new term has been recommended for use by many professional societies and included as a new thyroid tumor entity in WHO Classification of Tumours of Endocrine Organs from the World Health Organization published in 2017. Over the course of 18 months, more than 80 peer-reviewed publications have reported institutional experience with NIFTP. Methods | We reviewed English-language publications through PubMed (January 24, 2018), using a keyword search for NIFTP. We focused on large patient cohorts with tumors meeting the diagnostic criteria for NIFTP. Results | Five studies, all retrospective, reported large series of patients (>70) with NIFTP (Table). 2-6 The first 3 studies included 285 patients; they reported no tumor-related adverse events after a mean follow-up ranging from 5.8 to 11.2 years. 2-4 These series included patients with multifocal and bilateral tumors and those with large tumors (>4 cm), supporting the initial finding of indolent clinical behavior of NIFTP. However, 2 other studies reported that 4% to 6% of patients with nodules meeting the diagnostic criteria for NIFTP were found to have metastasis. 5,6 Many of these tumors had at least some papillary structures identified, revealed BRAF V600E mutation, and showed metastasis to regional lymph nodes and not distant sites. All of these features are characteristics of classic papillary thyroid carcinoma (PTC) and are rarely seen in an invasive encapsulated follicular variant of PTC, which is an invasive counterpart of NIFTP. The initial report that established NIFTP as a

Interobserver and intraobserver variation in the morphological evaluation of noninvasive follicular thyroid neoplasm with papillary‐like nuclear features in Asian practice

“…All the slides of each case were reviewed by three pathologists from the same institution and the final diagnosis of NIFTP was rendered morphologically. No papillae as recently described was found in all the slides of each cases . A series from Korea included three noninvasive follicular patterned thyroid tumors with minimal microscopic lymph node metastasis (<2 mm) and three cases with BRAF V600E mutation.…”

“…In addition, several recent institutional reports from the USA and Korea described NIFTP cases with BRAF V600E and TERT promoter mutations characteristic for conventional PTC . These controversial findings prompted ramifications of NIFTP diagnostic criteria released in 2018 . It is likely that the existing three‐point scoring system for evaluation of PTC type nuclear features is not able to exclude all PTC from NIFTP.…”

Follow‐up of noninvasive follicular thyroid neoplasm with papillary‐like nuclear features (NIFTP)

“…3 Although less intense that in patients with low-risk welldifferentiated carcinoma, we believe that the follow-up recently proposed by Ferris et al 4 for patients with NIFTP after its complete resection is not in line with the previous changes. Thus, (1) the name was changed (removing the term "cancer"), 1 (2) the nature of the lesion (no longer considered "cancer") was changed in the international tumor classification of the World Health Organization, 2 and (3) a rigorous diagnostic criterion was established, which has already been revised and became more restricted, eliminating many cases of NIFTP that had been reported with BRAF V600E mutations and metastases.…”

“…3 The original publication from 2016 itself was retrospective and excluded some cases initially considered noninvasive EFVPTC in the centers of origin. We agree with this concern, but we believe that these data may actually overestimate the malignant potential and risk of recurrence, that is, some cases previously diagnosed as noninvasive encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) would nowadays not meet the diagnostic criterion of NIFTP.…”

“…After removing the term "cancer" from the name, 1 changing the nature of the lesion (no longer "cancer"), 2 and establishing a rigorous diagnosis criterion that is clear, known, and accessible to every pathologist, 3 we are reluctant to endorse the recommendation suggested by Ferris et al 4 of periodic and long-term follow-up using tumor markers as a means of compensating for possible equivocal diagnoses. After removing the term "cancer" from the name, 1 changing the nature of the lesion (no longer "cancer"), 2 and establishing a rigorous diagnosis criterion that is clear, known, and accessible to every pathologist, 3 we are reluctant to endorse the recommendation suggested by Ferris et al 4 of periodic and long-term follow-up using tumor markers as a means of compensating for possible equivocal diagnoses.…”