J Pathol Transl Med.  2019 Nov;53(6):378-385. 10.4132/jptm.2019.09.18.

A Multi-institutional Study of Prevalence and Clinicopathologic Features of Non-invasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features (NIFTP) in Korea

• Seo JY
• Park JH
• Pyo JY
• Cha YJ
• Jung CK
• Song DE
• Kwak JJ
• Park SY
• Na HY
• Kim JH
• Seok JY
• Kim HS
• Hong SW

• KMID: 2465437
• DOI: http://doi.org/10.4132/jptm.2019.09.18

Abstract

BACKGROUND
In the present multi-institutional study, the prevalence and clinicopathologic characteristics of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) were evaluated among Korean patients who underwent thyroidectomy for papillary thyroid carcinoma (PTC).
METHODS
Data from 18,819 patients with PTC from eight university hospitals between January 2012 and February 2018 were retrospectively evaluated. Pathology reports of all PTCs and slides of potential NIFTP cases were reviewed. The strict criterion of no papillae was applied for the diagnosis of NIFTP. Due to assumptions regarding misclassification of NIFTP as non-PTC tumors, the lower boundary of NIFTP prevalence among PTCs was estimated. Mutational analysis for BRAF and three RAS isoforms was performed in 27 randomly selected NIFTP cases.
RESULTS
The prevalence of NIFTP was 1.3% (238/18,819) of all PTCs when the same histologic criteria were applied for NIFTP regardless of the tumor size but decreased to 0.8% (152/18,819) when tumors ≥1 cm in size were included. The mean follow-up was 37.7 months and no patient with NIFTP had evidence of lymph node metastasis, distant metastasis, or disease recurrence during the follow-up period. A difference in prevalence of NIFTP before and after NIFTP introduction was not observed. BRAF(V600E) mutation was not found in NIFTP. The mutation rate for the three RAS genes was 55.6% (15/27).
CONCLUSIONS
The low prevalence and indolent clinical outcome of NIFTP in Korea was confirmed using the largest number of cases to date. The introduction of NIFTP may have a small overall impact in Korean practice.

Keyword

Thyroid carcinoma; Follicular variant; Papillary carcinoma; Non-invasive follicular thyroid neoplasm with papillary-like nuclear features

MeSH Terms

Carcinoma, Papillary
Diagnosis
Follow-Up Studies
Genes, ras
Hospitals, University
Humans
Korea*
Lymph Nodes
Mutation Rate
Neoplasm Metastasis
Pathology
Prevalence*
Protein Isoforms
Recurrence
Retrospective Studies
Thyroid Gland*
Thyroid Neoplasms*
Thyroidectomy
Protein Isoforms

Figure

• 

  Fig. 1. (A) A case of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP): low power view, NIFTP composed entirely of a follicular growth pattern with complete encapsulation (scan view). (B) NIFTP shows a thick fibrous capsule without capsular and vascular invasion. (C) NIFTP with nuclear score 2. (D, E) Papillary thyroid carcinoma showing nuclear score 3.

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