Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features: From Echography to Genetic Profile

Abstract

In thyroid pathology, the great variety of types and the wide range of aggressiveness of thyroid cancers complicate both diagnosis and management. In 2016, a subset of noninvasive encapsulated follicular variant of papillary thyroid carcinoma was reclassified as noninvasive follicular thyroid tumor with papillarylike nuclear features (NIFTP) to reduce overtreatment of this low-risk tumor that follows a benign course after surgery. Starting from a paradigmatic clinical case, in this short review, we will summarize the ultrasonography, cytological, histological and molecular features of this new entity. In the preoperative settings, the recognition of some peculiar elements may only suggest the possibility of a NIFTP, thus favoring a less aggressive surgical approach. However, the diagnosis of NIFTP can only be made after complete resection of the lesion by detecting well-defined inclusion and exclusion histopathological criteria. Since NIFTP is not 'malignant,' surgery may be considered curative with no further treatment or surveillance needed. NIFTP-related issues, including nodule size, multifocality, oncocytic changes, heterogeneous incidence across different geographical areas and its occurrence in the pediatric age, will be discussed.

Non-Invasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features: Pitfalls of Cytological and Histopathologic Diagnosis

“…In the same histological background in regard NIFTP, this new entity must be differentiated histologically rather than cytologically from other thyroid neoplasms as follicular adenoma, EFVPTC, FT-UMP (follicular tumor of uncertain malignant potential), WDT-UMP (well-differentiated tumor with uncertain malignant potential) as well as recently introduced borderline tumor with papillary structure "NEPRAS,". The above pitfalls can be solved by the application of the diagnostic parameters of NIFTP, the diagnosis will be straightforward [44,10]. A study by Hirokawa and coworkers 2020 showed that in a Japanese retrospective case series, the peculiar differential diagnosis of NIFTP is follicular adenoma rather than other neoplasms [45].…”

“…Additionally a recent international multidisciplinary collaborative group agreed about this variant. Finally, this new entity was agreed by American Thyroid Association in their treatment recommendations [4][5][6][7][8][9][10][11]. By new nomenclature of NIFTP, the term thyroid carcinoma is avoided so, over-diagnosis and overtreatment of tumors with indolent biological behavior and a good prognosis will become clear and carries an excellent congratulation for patients [5].…”

“…The accurate diagnosis of NIFTP is tightly linked to histological sections following tumor resection. The diagnostic criteria included a unique features of this new entity was applied on this article [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. In the same manner a combination of triple ways included sonographical, cytologic and molecular tests can be suspecting preoperative diagnosis of NIFTP [19][20][21][22][23] (Tables 1 & 2); (Figures 1-3) [24,4,5,17,18,25].…”

“…B) Architecture of the nodule: a NIFTP as a prevalent microfollicular pattern of growth (up) and no papillae or psammoma bodies are allowed (down). C) Nuclear features: NIFTP have large, clear and irregular nuclei, with frequent grooves and occasional pseudoinclusions.NIFTP nuclei (right) differ significantly from regular nuclei of normal thyrocytes (left), which are small, rounded and dark[10].…”

Clinical-Pathological and Molecular Evaluation of 451 NIFTP Patients from a Single Referral Center

“…Moreover, a preoperative NIFTP diagnosis is extremely difficult, as they do not show peculiar ultrasound (US) nor cyto-morphological features [ 12 ]. On fine-needle aspiration (FNA), they are mostly classified as indeterminate nodules [ 13 ].…”