PURPOSE

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a premalignant tumor formerly known as non-invasive encapsulated follicular variant of papillary thyroid carcinoma. The aim of this study was to investigate the clinicopathological traits of NIFTP to discern them from well-differentiated cancers and potentially avoid overtreatment.

METHODS

We conducted a retrospective cohort study of NIFTP cases from July 2017 to November 2022 at our center. A review of demographic, clinical, sonographic, cytologic and surgical data was performed.

RESULTS

During the study period 70 NIFTP cases were included. Among the cohort 74.3% (52/70) were women and the mean age was 55 years (range, 25–84). The majority of patients presented euthyroid (92.9%). Median NIFTP size was 2.5 cm (range, 1.0-10.8). Most nodules displayed low or intermediate risk on ultrasound being labeled EU-TIRADS 3 (46/70, 65.7%) and EU-TIRADS 4 (23/70, 32.9%). In cytology they were typically diagnosed as Bethesda III (15/70, 21.4%) or Bethesda IV (41/70, 58.6%). Regarding surgical procedures, 36 patients (51.4%) underwent lobo-isthmectomy and 34 patients (48.6%) received total thyroidectomy. Thirteen patients (18.6%) had coexisting microcarcinomas. No patients received radioiodine ablation. After a median follow-up of 27.5 months, no structural or biochemical recurrences were observed.

CONCLUSION

Non-suspect thyroid nodules on preoperative ultrasound when combined with an indeterminate cytology and altered molecular profile should raise awareness towards the possibility of NIFTP. Even though neither FNAB nor CNB are definitive for NIFTP, CNB may be considered when additional architectural assessment is needed. Management with lobectomy seems to suffice unless total thyroidectomy is justified.