Revised criteria for diagnosis of NIFTP reveals a better correlation with tumor biological behavior

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de Jesus Paniza, Ana Carolina ; Mendes, Thais Biude ; Borges Vianna, Matheus Duarte ; Dias Thomaz, Debora Mota ; Chiappini, Paula B. O. ; Colazza-Gama, Gabriel A. ; Lindsey, Susan Chow ; de Carvalho, Marcos Brasilino ; Ferreira Alves, Venancio Avancini ; Curioni, Otavio ; Bastos, Andre Uchimura ; Cerutti, Janete Maria

• Document type: Journal article
• Source: ENDOCRINE CONNECTIONS; v. 8, n. 11, p. 10-pg., 2019-11-01.

Abstract

The recent reclassification of a follicular variant of papillary thyroid carcinoma (FVPTC), subset as noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), aims to avoid overtreatment of patients with an indolent lesion. The diagnosis of NIFTP has recently been revisited using more rigid criteria. This study presents histological and molecular findings and a long clinical follow-up of 94 FVPTC, 40 cases of follicular adenoma (FTA) and 22 cases of follicular carcinoma (FTC) that were classified before the advent of the NIFTP reclassification. All slides were reviewed using these rigid criteria and analysis of numerous sections of paraffin blocks and reclassified as 7 NIFTPs, 2 EFVPTCs, 29 infiltrative FVPTC (IFVPTCs), 57 invasive EFVPTC (I-EFVPTCs), 39 FTAs and 22 FTCs. Remarkably, EFVPTC and NIFTP patients were all free of disease at the end of follow-up and showed no BRAF mutation. Only one NIFTP sample harbored mutations, an NRAS Q61R. PAX8/PPARG fusion was found in I-EFVPTCs and FTC. Although additional studies are needed to identify a specific molecular profile to aid in the diagnosis of lesions with borderline morphological characteristics, we confirmed that the BRAFV600E mutation is an important tool to exclude the diagnosis of NIFTP. We also show that rigorous histopathological criteria should be strongly followed to avoid missing lesions in which more aggressive behavior is present, mainly via the analysis of capsule or vascular invasion and the presence of papillary structures. (AU)

• FAPESP's process: 14/06570-6 - Comprehensive whole exome, paired-end RNA and genome sequencing: new insights into genetic bases of thyroid carcinoma in pediatric and adult ages and applications in clinical practice
• Grantee: Janete Maria Cerutti
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/25784-2 - Resistance mechanisms to treatment with temozolomide in glioma cells
• Grantee: André Uchimura Bastos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 17/16315-1 - Analysis of the prevalence of STRN-ALK rearrangement in Hürthle cell tumors
• Grantee: Débora Mota Dias Thomaz
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 17/06487-0 - Identification of the metabolic profile of cells with ectopic expression of PVALB and investigation of the molecular mechanism associated with its expression in Hürthle cell adenomas
• Grantee: Thais Biude Mendes
• Support Opportunities: Scholarships in Brazil - Doctorate