Endocrine Abstracts

Introduction: NIFTP (non invasive follicular neoplasm of the thyroid with papillary-like nuclear features, formerly noninvasive encapsulated follicular variant of papillary thyroid carcinoma) has been removed from the carcinoma category due to its indolent nature and its good prognosis. The purpose of our study was to identify preoperative ultrasound and cytological differences between NIFTP and papillary thyroid carcinoma (PTC).

Materials and methods: retrospective study including patients followed in the endocrinology department of the CHU Ibn Rochd in Casablanca, from 2017 to 2021, with histological diagnosis of PTC or NIFTP

Results: A total of 113 cases, including 27 NIFTPs, 86 papillary carcinomas, were observed. The 14 NIFTPs involved 24 women and 3 men, with an average age of 51.9 years, 2 patients had a history of familial thyroid carcinoma. The majority of patients (n=24) were euthyroid, 3 were hyperthyroid. Preoperative cytological data were available for 11 cases. Compared to papillary carcinomas, nodules corresponding to NIFTPs are more isoechogenic (59.3% vs 8.1%; P≤0.001), have regular contours (85.2% vs 52.3%; P≤0.01) and have a TIRADS score 3 (48.1% vs 8.1%; P≤0.001), TIRADS 4 (40.7% vs 43%) or TIRADS 5 (7.4% vs 48.8%). Cytologically, NIFTPs are preferentially distributed in categories III (18% vs. 3.8%), IV (9% vs. 11.5%) and V (36.3% vs. 38.4%) of the Bethesda classification without significant difference compared to papillary carcinoma (P≤ 0.9).

Conclusion: NIFTPs appear mostly non-suspicious on preoperative ultrasound and of indeterminate significance on cytology. These differences compared to papillary carcinomas can make it possible to suspect the diagnosis preoperatively and to better adapt the surgical management.