title: Cytological features of "noninvasive follicular thyroid neoplasm with papillary-like nuclear features" and their correlation with tumor histology.
abstract: Among thyroid papillary carcinomas (PTCs), the follicular variant is the most common and includes encapsulated forms (EFVPTCs). Noninvasive EFVPTCs have very low risk of recurrence or other adverse events and have been recently proposed to be designated as noninvasive follicular thyroid neoplasm with papillary-like nuclear features or NIFTP, thus eliminating the term carcinoma. This proposal is expected to significantly impact the risk of malignancy associated with the currently used diagnostic categories of thyroid cytology. In this study, we analyzed the fine needle aspiration biopsy (FNAB) cytology features of 96 histologically proven NIFTPs and determined how the main nuclear features of NIFTP correlate between cytological and histological samples. Blind review of FNAB cytology from NIFTP nodules yielded the diagnosis of "follicular neoplasm" (Bethesda category IV) in 56% of cases, "suspicious for malignancy" (category V) in 27%, "atypia of undetermined significance/follicular lesion of undetermined significance" (category III) in 15%, and "malignant" (category VI) in 2%. We found good correlation (κ=0.62) of nuclear features between histological and cytological specimens. NIFTP nuclear features (size, irregularities of contours, and chromatin clearing) were significantly different from those of benign nodules but not from those of invasive EFVPTC. Our data indicate that most of the NIFTP nodules yield an indeterminate cytological diagnosis in FNAB cytology and nuclear features found in cytology samples are reproducibly identified in corresponding histology samples. Because of the overlapping nuclear features with invasive EFVPTC, NIFTP cannot be reliably diagnosed preoperatively but should be listed in differential diagnosis of all indeterminate categories of thyroid cytology.
authors.affiliation: Division of Pathology, Città della Salute e della Scienza Hospital, Department of Oncology, University of Turin, Turin 10126, Italy. Electronic address: francesca.maletta@unito.it.
authors.forename: Francesca
authors.initials: F
authors.lastname: Maletta
authors.affiliation: Division of Pathology, Città della Salute e della Scienza Hospital, Department of Oncology, University of Turin, Turin 10126, Italy. Electronic address: federica.massa@edu.unito.it.
authors.forename: Federica
authors.initials: F
authors.lastname: Massa
authors.affiliation: Division of Anatomic Pathology 3, Azienda Ospedaliero-Universitaria Pisana, University of Pisa, Pisa 56126, Italy. Electronic address: libo.torregrossa@gmail.com.
authors.forename: Liborio
authors.initials: L
authors.lastname: Torregrossa
authors.affiliation: Division of Pathology, Department of Oncology, University of Turin at San Luigi Hospital, Orbassano, 10043, Turin, Italy. Electronic address: eleonora.duregon@unito.it.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Duregon
authors.affiliation: Division of Pathology, Ospedale Maggiore, Bologna 40133, Italy. Electronic address: gianpiero.casadei@ausl.bologna.it.
authors.forename: Gian Piero
authors.initials: GP
authors.lastname: Casadei
authors.affiliation: Division of Anatomic Pathology 3, Azienda Ospedaliero-Universitaria Pisana, University of Pisa, Pisa 56126, Italy. Electronic address: fulvio.basolo@med.unipi.it.
authors.forename: Fulvio
authors.initials: F
authors.lastname: Basolo
authors.affiliation: Department of Pathology, University of Bologna Medical School, Bologna 40139, Italy. Electronic address: giovanni.tallini@ausl.bologna.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tallini
authors.affiliation: Division of Pathology, Department of Oncology, University of Turin at San Luigi Hospital, Orbassano, 10043, Turin, Italy. Electronic address: marco.volante@unito.it.
authors.forename: Marco
authors.initials: M
authors.lastname: Volante
authors.affiliation: Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh 15213, USA. Electronic address: nikiforovye@upmc.edu.
authors.forename: Yuri E
authors.initials: YE
authors.lastname: Nikiforov
authors.affiliation: Division of Pathology, Città della Salute e della Scienza Hospital, Department of Oncology, University of Turin, Turin 10126, Italy. Electronic address: mauro.papotti@unito.it.
authors.forename: Mauro
authors.initials: M
authors.lastname: Papotti
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000737:chemistry / Q000145:classification / Q000473:pathology* / Q000628:therapy; D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis; D044963:Biopsy, Fine-Needle; D019002:CD56 Antigen / Q000032:analysis; D002277:Carcinoma / Q000737:chemistry / Q000145:classification / Q000473:pathology* / Q000628:therapy; D002291:Carcinoma, Papillary; D002467:Cell Nucleus / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007558:Italy; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D012189:Retrospective Studies; D009626:Terminology as Topic; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000737:chemistry / Q000145:classification / Q000473:pathology* / Q000628:therapy
chemical_list: D014408:Biomarkers, Tumor; D019002:CD56 Antigen; C522918:NCAM1 protein, human
keywords: Cytology; Encapsulated; Follicular variant papillary carcinoma; NIFTP; Thyroid cancer; Thyroid nodules