Non-Invasive Follicular Thyroid Neoplasm With Papillary-Like Nuclear Features (NIFTPs)

Over the past few years, follicular-patterned thyroid nodules with nuclear features of papillary thyroid carcinoma (PTC) have been further subclassified based on molecular profiling, histologic features, and clinical behavior. Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTPs) was established as a distinct entity in the 2017 4th edition of the WHO Classification of Tumors of Endocrine Organs due to its indolent clinical behavior and excellent prognosis. These tumors are characterized by a well-defined border, an exclusive follicular growth pattern, and PTC nuclear features. Molecularly, NIFTPs typically harbor RAS gene mutations, PAX8-PPARG rearrangements, or THADA gene fusions. In the 2022 5th edition of the WHO Classification, subcentimeter NIFTPs and oncocytic NIFTPs were introduced as new subtypes. In this review, we summarize the epidemiology, ultrasound features, histology/cytology, and molecular characteristics of NIFTP. As research continues to refine diagnostic criteria and management approaches, recognizing the distinct molecular and clinical features of NIFTP is essential for optimizing patient care and ensuring appropriate surgical management.