Non-Invasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP) in the Adolescent and Young Adult Population: A Pediatric Center Experience.

Abstract

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a well-demarcated tumor with follicular growth pattern and papillary thyroid carcinoma-like nuclear features. Only rare reports exist in the literature describing the clinicopathologic features and incidence of NIFTP in the adolescent and young adult age group. The aim of this study is to address these gaps in the literature and characterize NIFTPs arising in this population. We retrieved all cases of NIFTP diagnosed from 2017-2023 at the UPMC Children's Hospital of Pittsburgh. Clinical information, cytologic and histologic features, and molecular testing results were reviewed, alongside a literature review. We identified 10 cases of NIFTP in 8 females and 2 males with an age distribution of 15 to 26 years old out of 152 fine needle aspirates (6.6%). All nodules were classified as low to moderate malignant risk on sonography (TI-RADS 3 and 4: n=5 each). Cytologic reporting varied with Bethesda III (n=6) and IV (n=2) predominately. All cases exhibited RAS (n=7) or RAS-like (n=3) alterations on molecular testing. No disease recurrence was noted on follow-up (13-86 months, median 39 months). We describe the clinicopathologic and molecular features of NIFTP in our adolescent and young adult cohort and compare them with those published in the literature. We demonstrate that NIFTP is rare in young children and largely restricted to adolescents and young adults. Clinicopathologic features and behavior show marked resemblance to those of adult-diagnosed NIFTP and thus may benefit from similar conservative treatment modalities.