New terminology-noninvasive follicular neoplasm with papillary-like nuclear features (NIFTP) and its effect on the rate of malignancy at a single institution.

Kiernan CM, Weiss VL, Mehrad M, Ely K, Baregamian N, Solórzano CC
Surgery. 2018 163 (1): 55-59

PMID: 29126555 · DOI:10.1016/j.surg.2017.04.041

BACKGROUND - The cytologic qualities of noninvasive follicular neoplasm with papillary-like nuclear features mimic papillary thyroid carcinoma (PTC) on fine-needle aspiration, leading to difficulty in distinguishing the 2 preoperatively. The aim of this study was to determine the impact of reclassification of noninvasive follicular neoplasm with papillary-like nuclear features at our practice.

METHODS - We searched 1,046 patient charts for those cases with preoperative cytology and subsequent follicular-variant papillary thyroid carcinoma diagnosis on resection. Endocrine pathologists reviewed the cases to determine the reclassification of noninvasive follicular neoplasm with papillary-like nuclear features.

RESULTS - Sixty (6%) follicular-variant papillary thyroid carcinomas were identified, 4% (44) in the index nodule. Of the 44 patients, 84% (37) met the criteria for evaluation. Of these, 46% (17) were noninvasive follicular neoplasm with papillary-like nuclear features. After reclassification of noninvasive follicular-variant papillary thyroid carcinoma to noninvasive follicular neoplasm with papillary-like nuclear features, the overall cancer rate changed from 31% to 29%. Malignancy rates across Bethesda cytologic categories changed as follows: benign (n = 419) from 3.5% to 3.3%; atypia of undetermined significance/follicular lesion of undetermined significance (n = 240) from 17% to 15%; suspicious for follicular neoplasm (n = 104) from 23% to 21%; suspicious for malignancy (n = 85) from 68% to 60%, and malignant (n = 198) from 93% to 92%.

CONCLUSION - Reclassification of noninvasive follicular neoplasm with papillary-like nuclear features led to a small decrease in the overall malignancy rate. The most affected Bethesda category was suspicious for malignancy. Because the majority of noninvasive follicular neoplasm with papillary-like nuclear features will be indeterminate lesions by cytology/molecular testing, thyroidectomy will remain a common treatment modality. Noninvasive follicular neoplasm with papillary-like nuclear features classification will primarily affect decision making to avoid excessive treatment/monitoring.

Copyright © 2017 Elsevier Inc. All rights reserved.

MeSH Terms (12)

Adult Carcinoma, Papillary Diagnosis, Differential Female Humans Male Middle Aged Retrospective Studies Terminology as Topic Thyroid Cancer, Papillary Thyroid Gland Thyroid Neoplasms

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