Endocrine Abstracts

Introduction: Non-invasive follicular neoplasm with nuclear features of papillary carcinoma ‘NIFTP’, formerly encapsulated non-invasive follicular variant of papillary carcinoma, has been removed from the carcinoma category due to its indolent nature and good prognosis. This change impacts clinical and therapeutic care.

Objective of the work: To identify preoperative ultrasound and cytological differences between NIFTP and papillary carcinoma (PTC).

Material and methods: retrospective study includes 153 patients who underwent total thyroidectomy or lobectomy with a histological diagnosis of papillary carcinoma, NIFTP or invasive follicular variant of papillary carcinoma, between 2019 and 2023. Data from ultrasound and cytology were analyzed and compared between NIFTP and non-NIFTP (papillary carcinoma and invasive follicular variant of papillary carcinoma).

Results: Our study included 45 NIFTP, 108 papillary carcinomas including 47 follicular variants. Compared to papillary carcinomas, the nodules corresponding to NIFTP are more isoechoic (69.2% vs 17.4%, P=.0007) and have regular contours (92.3% vs 31.1%, P=.0001) and have an EU-TIRADS score 3 or 4. Cytologically, NIFTPs are classified categories III, IV and V of the Bethesda classification, while CPTs are mainly classified in categories V and VI of the Bethesda classification. Bethesda. Only the presence of nuclear pseudo-inclusions isemerged as significantly associated with the non-NIFTP group (P=0.0031).

Conclusion: NIFTPs appear mostly non-suspicious on pre-operative ultrasound with absence of nuclear inclusions on cytopuncture. These differences compared to papillary carcinomas can make it possible to suspect the diagnosis preoperatively and to best adapt surgical management towards more conservative management.