title: Can noninvasive follicular thyroid neoplasm with papillary-like nuclear features be distinguished from classic papillary thyroid carcinoma and follicular adenomas by fine-needle aspiration?
abstract: BACKGROUND
  Noninvasive encapsulated follicular variant of papillary thyroid carcinoma, a diagnosis implying malignancy as a variant of papillary thyroid carcinoma (PTC), has recently been reclassified to noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) on surgical pathology. Due to the effects of such a recategorization on rate of malignancy and clinical management algorithms, it is imperative that we explore whether presurgical fine-needle aspiration can differentiate NIFTP from PTC and follicular adenoma (FA).
  
  
  METHODS
  Cytology slides from subjects with final surgical pathology resection diagnoses of NIFTP/encapsulated follicular variant of papillary thyroid carcinoma, classic PTC, and FA made between January 2013 and August 2016 were assessed. The Bethesda System diagnoses were tabulated and cytomorphologic features were analyzed for an association with surgical pathology diagnoses.
  
  
  RESULTS
  A total of 56 NIFTP, 67 classic PTC, and 30 FA cases were included. The presurgical NIFTP diagnosis according to The Bethesda System was most often atypia of undetermined significance (37.5%) followed by suspicious for follicular neoplasm/follicular neoplasm (26.8%), suspicious for malignancy (17.9%), benign (10.7%), and positive for malignancy (7.1%). The most common NIFTP cytomorphologic features were nuclear enlargement (83.9%), nuclear crowding (82.1%), nuclear clearing (69.6%), and microfollicles (73.2%). All cytomorphologic features demonstrated statistically significant associations (P value range, <.001-.002) between NIFTP and PTC, whereas select cytomorphologic features demonstrated significant associations between NIFTP and FA.
  
  
  CONCLUSIONS
  Several statistically significant associations appear to be present between cytomorphologic features and surgical diagnosis that may be used as clues to distinguish NIFTP, PTC, and FA on fine-needle aspiration. Although diagnostic confirmation of NIFTP must occur at the time of excision, similar to follicular neoplasms, the possibility of NIFTP may be raised preoperatively on cytology. Cancer Cytopathol 2017;125:378-88. © 2017 American Cancer Society.
authors.affiliation: Department of Pathology, New York University Langone Medical Center, New York, New York.
authors.forename: Tamar C
authors.initials: TC
authors.lastname: Brandler
authors.affiliation: Department of Pathology, New York University Langone Medical Center, New York, New York.
authors.forename: Fang
authors.initials: F
authors.lastname: Zhou
authors.affiliation: Department of Pathology, New York University Langone Medical Center, New York, New York.
authors.forename: Cheng Z
authors.initials: CZ
authors.lastname: Liu
authors.affiliation: Department of Pathology, New York University Langone Medical Center, New York, New York.
authors.forename: Margaret
authors.initials: M
authors.lastname: Cho
authors.affiliation: Department of Pathology, New York University Langone Medical Center, New York, New York.
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Lau
authors.affiliation: Department of Pathology, New York University Langone Medical Center, New York, New York.
authors.forename: Aylin
authors.initials: A
authors.lastname: Simsir
authors.affiliation: Department of Endocrine Surgery, New York University Langone Medical Center, New York, New York.
authors.forename: Kepal N
authors.initials: KN
authors.lastname: Patel
authors.affiliation: Department of Pathology, New York University Langone Medical Center, New York, New York.
authors.forename: Wei
authors.initials: W
authors.lastname: Sun
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery; D000236:Adenoma / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery; D044963:Biopsy, Fine-Needle; D002277:Carcinoma / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery; D002291:Carcinoma, Papillary; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D012189:Retrospective Studies; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery
keywords: The Bethesda System; cytomorphology; fine-needle aspiration; noninvasive encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC); noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP)