The data clearly show that the ROM of a benign aspirate is about 3% (even when NIFTP
is taken into account, because most of these cases are the result of inadequate sampling of classical malignancies), whereas the ROCSD based on clinical follow-up of patients with benign aspirates approaches zero.
In the current endocrine surgical practice environment we lack prospective studies that provide guidance for the surgical management of patients with suspected noninvasive EFVPTCs and/or NIFTP
tumors (collectively referred to as "encapsulated follicular tumors").
Grossly, NIFTP appears as a solid well-circumscribed or encapsulated nodule.
The histological diagnosis of NIFTP is made using strict inclusion and exclusion criteria following submission of the entire tumor capsule for histology and careful examination of nuclear features, as well as overall architecture.
The introduction of the NIFTP nomenclature has posed a potential problem for cytopathologists.
Sonographic and cytologic differences of NIFTP
from infiltrative or invasive encapsulated follicular variant of papillary thyroid carcinoma: a review of 179 cases.
Given the heterogeneous and controversial nature of PTC-FV, and in light of the recognition of NIFTP by the WHO, (17) we evaluated all subtypes of PTC-FV historically diagnosed at our institution and compared their morphologic and genetic features to benign follicular adenomas (FAs).
A benign (FA) diagnosis was rendered if the nodule demonstrated follicular growth, circumscription with no evidence of invasion, and insufficient nuclear features as proposed for NIFTP (see below).
A diagnosis of NIFTP was rendered if the nodule showed circumscription with no evidence of invasion (capsular, vascular, or intrathyroidal), less than 1% true papillae (defined as complex, arborizing papillae with fibrovascular cores ...
(35,36) Indeed, many mutations, such as BRAF V600E and RET/PTC, confer a close to 100% probability of cancer, whereas other mutations, such as RAS, are diagnostic of a clonal tumor with ~80% probability of typically low-risk cancer or NIFTP, as discussed later in this review.
Considering NIFTP in the malignant category, the prevalence of malignancy in this cohort was 20%.
(3) For nodules with RAS and other RAS-like mutations, which confer a high probability of either low-risk cancer or precancer NIFTP, diagnostic lobectomy may represent the optimal surgical approach.