Comparing Clinicopathologic and Radiographic Findings Between TT-UMP, Classical, and Non-Encapsulated Follicular Variants of Papillary Thyroid Carcinomas

Abstract

Thyroid tumors of uncertain malignant potential (TT-UMP) comprise an accepted subgroup of follicular-patterned thyroid tumors for which benignancy or malignancy cannot be precisely assessed. We aimed to evaluate the demographic characteristics, ultrasound (US) findings, and cytological results of patients with TT-UMP and compare these findings to a classical variant of papillary thyroid carcinoma (CV-PTC) and non-encapsulated follicular variant of PTC (NEFV-PTC) patients; we also evaluated the immunohistochemical characteristics of patients with TT-UMP. Twenty-four patients with TT-UMP, 672 with CV-PTC, and 132 with NEFV-PTC were included in the study. Mean longitudinal nodule size and median nodule volume were higher in the TT-UMP group than in the CV-PTC and NEFV-PTC groups (p < 0.001 and p < 0.001 for CV-PTC; p < 0.001 and p = 0.008 for NEFV-PTC). The presence of halo and peripheral vascularization was observed more frequently in the TT-UMP group than in the CV-PTC group (p = 0.002 and p = 0.024). Benign and follicular neoplasm/suspicious for follicular neoplasm cytological results were higher in the TT-UMP group than in the CV-PTC group (p = 0.030 and p = 0.001). US findings were similar between TT-UMP and NEFV-PTC groups (all, p > 0.05). However, none of the patients with TT-UMP were called malignant; 105 patients (31.2 %) of CV-PTC and 11 patients (9.5 %) of NEFV-PTC (infiltrative FV) were classified as malignant cytologically. Tumor size was higher in the TT-UMP group than in the CV-PTC and NEFV-PTC groups (p < 0.001 and p = 0.006). In the TT-UMP group, positive expression of HBME-1, CK-19, and Gal-3 was found in 50, 33.3, and 25 % of patients, respectively. This study demonstrated that none of the TT-UMP patients were evaluated as malignant in preoperative cytology. However, patients with TT-UMP had higher nodule and tumor sizes than CV-PTC and NEFV-PTC patients; US features were similar between NEFV-PTC and TT-UMP patients.

Noninvasive follicular thyroid neoplasm with papillary‐like nuclear features (NIFTP): Implications for the risk of malignancy (ROM) in the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC)

“…We also compared the previous matched FNAC diagnosis for the histopathology diagnosis of NIFTP, both in our current study and in previously published reports (Table ) . For the benign category, NIFTP correlations with prior FNA diagnosis varied widely (benign, 0%‐30.4%; AUS/FLUS, 5.2%‐61%; FN/SFN, 3.9%‐40.6%; SM, 0%‐41.5%; and M, 0%‐12.7%).…”

“…The reporting rate of NIFTP on histopathology is quite variable in the published data, 17,18,23,[25][26][27][28] which may be caused by multiple factors, including patient demographics, referral patterns, and the diagnostic threshold of individual cytopathologists and surgical pathologists. Currently, FVPTC represents a significant proportion (approximately 15%-20%) of PTC diagnoses with increasing incidence.…”

“…The aggregate data from this study were compared with previously published reports and professional society meeting abstracts ( We also compared the previous matched FNAC diagnosis for the histopathology diagnosis of NIFTP, both in our current study and in previously published reports (Table 5). 17,18,23,[25][26][27][28] For the benign category, NIFTP correlations with prior FNA diagnosis varied widely (benign, 0%-30.4%; AUS/FLUS, 5.2%-61%; FN/SFN, 3.9%-40.6%; SM, 0%-41.5%; and M, 0%-12.7%).…”

Cytopathology of non‐invasive follicular thyroid neoplasm with papillary‐like nuclear features: A comparative study with similar patterned papillary thyroid carcinoma variants

“…In contrast to the microfollicular architecture of NIFTP, cPTC cells are distributed chiefly in sheets and papillae, and show prominent nuclear features including grooves and more frequent and easily identifiable INI, and psammomatous calcification . cPTC is more likely to be categorised into the highest TBSRTC categories (SFM and malignant) as compared to NIFTP, which usually falls into one of the intermediate categories (AUS/FLUS, FN/SFN, SFM; Table ) . We compared NIFTP cytology with that of cPTC showing a predominant follicular pattern (PTC‐FP).…”

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

“…Studies to date have shown that cytomorphologically, NIFTPs tend to show a predominant microfollicular architecture composed of cells with irregular nuclear borders and chromatin clearing and an absence of papillae and pseudoinclusions . Since NIFTPs or their former equivalent (NEFVPTCs) typically do not show the full range of nuclear features seen in classic type PTCs, particularly when the atypia is subtle or focal, they are frequently assigned an indeterminate cytological diagnosis within the TBSRTC classification system (Table ). In our study, of the 72 cases of NIFTP with a prior cytological diagnosis, 40.3% were classified as AUS/FLUS and 37.5% as FN/SFN/FNOF.…”