Impact of Reclassification on Thyroid Nodules with Architectural Atypia: From Non-Invasive Encapsulated Follicular Variant Papillary Thyroid Carcinomas to Non-Invasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features

Abstract

BackgroundThe follicular variant of papillary thyroid cancer (FVPTC), especially the encapsulated non-invasive subtype, is a controversial entity. Recent study suggested using ‘non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP)’ for these indolent carcinomas. We evaluated the impact of reclassification from non-invasive encapsulated FVPTCs (EFVPTCs) to NIFTPs in the diagnosis of thyroid nodules with architectural atypia.MethodsWe reviewed 1301 thyroid nodules with architectural atypia in core needle biopsy (CNB) specimens obtained from March 2012 to February 2013. Nodules were classified into atypia of undetermined significance with architectural atypia (AUS-A, 984, 76%) or follicular neoplasm/suspicious for a follicular neoplasm (FN/SFN, 317, 24%). Among them, diagnostic surgery was performed in 384 nodules (30%).ResultsIn total, 160 nodules (42%) presented final malignant diagnoses including 39 non-invasive encapsulated FVPTCs (10%). The malignancy rate was estimated to be 7–35% in AUS-A nodules and 28–49% in FN/SFN nodules. After reclassification, the malignancy rate was much decreased and estimated to be 5–24% in AUS-A nodules, and 23–39% in FN/SFN nodules. Thyroid nodules with final malignant diagnoses were significantly more likely to have a FN/SFN CNB diagnosis, malignant US features and concomitant nuclear atypia in CNB specimens. However, these factors could not differentiate NIFTPs from other malignancies.ConclusionsAfter reclassification of non-invasive EFVPTCs to NIFTPs, the malignancy rate of thyroid nodules with architectural atypia in CNB specimens was decreased. However, there were no preoperative factors differentiating other malignancies from NIFTPs. The presence of malignant US features or concomitant nuclear atypia might help clinicians deciding diagnostic surgery but, these features also might indicate NIFTPs.

Noninvasive follicular neoplasm with papillary like nuclear features: A comprehensive analysis with a diagnostic algorithm

“…In spite of Asian continent being a major contributor to worldwide prevalence of thyroid cancer (according to GLOBOCON database; estimated 48% new cases in 2012), the prevalence of NIFTP in Asians has not been reported extensively as compared with the western world . There are limited studies from Asia and even fewer form India and those present have reported a significantly lower prevalence (0%‐5%) as compared to western data (15%‐25%) …”

The impact of the non‐invasive follicular thyroid neoplasm with papillary‐like nuclear feature terminology in the routine diagnosis of thyroid tumours

“…In our series, the cytological diagnoses in the NIFTP cases were mainly Thy3/Bethesda III‐IV, while the cases of i‐fvPTC were found more frequently in Thy4/V and Thy5/VI. In indeterminate cases, a general discussion still persists regarding the best surgical approach (hemi vs total thyroidectomy) for the patients . The aim of modern classification systems is to predict the nature of diseases, whether benign or malignant, and in order to do this, increasingly sophisticated and often translational methods are employed.…”

“…Moreover, investigating how new histological criteria may affect preoperative cytological reporting schemes is becoming of growing interest. [7][8][9] In the following paradigmatic series, the authors demonstrate how the new classification has been spread in general hospitals. The main aim of the study was to evaluate the incidence of the NIFTP category.…”

“…Given that 1 year has passed since the introduction of the new classification in routine practice, pathologists now need to evaluate whether a certain degree of disagreement still persists or whether the new criteria have really improved the diagnosis. Moreover, investigating how new histological criteria may affect preoperative cytological reporting schemes is becoming of growing interest . In the following paradigmatic series, the authors demonstrate how the new classification has been spread in general hospitals.…”

Pre‐operative features of non‐invasive follicular thyroid neoplasms with papillary‐like nuclear features: An analysis of their cytological, Gene Expression Classifier and sonographic findings

“…The immediate benefits include but are not limited to avoidance of overtreatment, leading to a decrease in unnecessary medical spending, and reducing the psychological burden of receiving a cancer diagnosis . Many authors have also predicted a decrease in the risk of malignancy, particularly for the three indeterminate diagnostic categories of The Bethesda System for Reporting Thyroid Cytopathology (TBSRTC) …”