Clinicopathological parameters for predicting non-invasive follicular thyroid neoplasm with papillary features (NIFTP)

Eunju Jang; Kwangsoon Kim; Chan Kwon Jung; Ja Seong Bae; Jeong Soo Kim

doi:10.1177/20420188211000500

Clinicopathological parameters for predicting non-invasive follicular thyroid neoplasm with papillary features (NIFTP)

Ther Adv Endocrinol Metab. 2021 Apr 12:12:20420188211000500. doi: 10.1177/20420188211000500. eCollection 2021.

Authors

Eunju Jang¹, Kwangsoon Kim², Chan Kwon Jung³, Ja Seong Bae¹, Jeong Soo Kim⁴

Affiliations

¹ Department of Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea.
² Department of Surgery, College of Medicine, The Catholic University of Korea, 222 Banpodaero, Seoul, 06591, Korea.
³ Department of Hospital Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
⁴ Department of Surgery, College of Medicine, The Catholic University of Korea, Seoul, 06591, Korea.

Abstract

Background: Criteria for the preoperative diagnosis of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) have not yet been confirmed. This study aimed to analyze differences in clinicopathological characteristics between follicular variant of papillary thyroid carcinoma (FVPTC) subtypes to determine which parameters are relevant in differentiating NIFTP from other variants.

Methods: We retrospectively analyzed the records of 199 patients with a preoperative diagnosis of FVPTC who underwent thyroid surgery at Seoul St. Mary's Hospital (Seoul, Korea) from 2011 to 2015. Clinicopathological features were analyzed retrospectively via a complete review of medical charts and pathology reports of patients.

Results: The NIFTP and invasive encapsulated FVPTC (EFVPTC) groups showed relatively benign features, with a majority of the patients categorized as Bethesda category III (25.8% and 25.6%, respectively) or IV (34.8% and 30.2%, respectively), while the infiltrative FVPTC group showed more malignant features, with more patients categorized as category V (28.6%) or VI (47.6%) (p < 0.001). BRAF ^V600E mutations were significantly less prevalent in the NIFTP group (0%) and invasive EFVPTC group (4.7%) compared with the infiltrative FVPTC group (34.9%) (p < 0.001). Multivariate analysis showed that absence of BRAF ^V600E mutation (OR 20.311, p = 0.004) and lymph node metastasis (odds ratio 10.237, p = 0.004) were significantly associated with NIFTP.

Conclusion: Although Bethesda category was a statistically significant factor in distinguishing FVPTC subtypes, it was not effective in conclusively distinguishing NIFTP and invasive EFVPTC. Absence of BRAF ^V600E mutation and lymph node metastasis are important features in distinguishing NIFTP from other subtypes.

Keywords: NIFTP; follicular variant; papillary thyroid carcinoma; thyroidectomy.