How Does Noninvasive Follicular Thyroid Neoplasm With Papillary-Like Nuclear Features (NIFTP) Compare to Encapsulated and Nonencapsulated Follicular Variants of Papillary Thyroid Carcinoma? An Examination Into Next-Generation Sequencing Molecular Profiles

Abstract

Abstract Objectives With the removal of noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) from the follicular variant of papillary thyroid carcinoma (FVPTC) categorization, the question arises as to how the molecular profile of invasive encapsulated FVPTC (IEFVPTC) compares with NIFTP. Our study aimed to examine the molecular alterations associated with NIFTP, IEFVPTC, and infiltrative FVPTC (iFVPTC) to determine whether these entities are actually distinct at the molecular level. Methods Forty-five NIFTP cases, 12 IEFVPTC cases, and 8 iFVPTC cases from 1/2013 to 8/2016 were assessed for presurgical fine-needle aspiration ThyroSeq V2 next-generation sequencing results. Results The NIFTP cases displayed alterations in BRAF K601E/EIF1AX, BRAF T599_R603, NRAS x15 (two with additional PTEN and one with P53), KRAS x3, HRAS x11 (one with an additional TERT/EIF1AX), PAX8-PPARgamma x5, PTEN, THADA x3, MET x2, copy number alteration, EF1AX, and DICER1. The IEFVPTC displayed alterations in RAS x5 (1 NRAS/TERT, 2 HRAS, 2 NRAS), BRAF-K601E x2, and BRAF-pG469A with gene expression profile; PAX8-PPARgamma x2; THADA-IGF2BP3; and ETV6/NTRK3. The iFVPTC cases displayed alterations in RAS x2 (NRAS and HRAS), TERT x2, BRAF-V600E mutation, ALK, MET, and NTRK3. Conclusion NIFTP and IEFVPTC cases most commonly displayed RAS mutations (64.4% and 41.7%, respectively) and lacked aggressive BRAF-V600E mutations, whereas iFVPTC harbored aggressive mutations such as BRAF-V600E and TERT more commonly, with fewer RAS mutations. The possibility of NIFTP and IEFVPTC being on a premalignant to malignant continuum must be raised and these entities may be more similar to each other than to other entities such as iFVPTC.