Follicular morphological characteristics may be associated with invasion in follicular thyroid neoplasms with papillary-like nuclear features

Abstract

The newly proposed nomenclature and diagnostic criteria for encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC), the noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), could improve the consistency and accuracy of diagnosing this entity. Diagnosis of NIFTP requires evaluation of the complete tumor border or capsule. The presence of tumor invasion in follicular thyroid neoplasms with papillary-like nuclear features has been recently discussed by many authors. In this study, we examined the predictive value and association of follicular morphological characteristics with the tumor invasion. In addition, we analyzed the association between tumor encapsulation and molecular profile in EFVPTC/NIFTP cases. A total of 106 cases of FVPTC were included in the study. The tumors were grouped based on the presence of tumor capsule and characteristics of tumor border, as 1) completely encapsulated tumors without invasion, 2) encapsulated tumors with invasion, 3) infiltrative tumors without a capsule. Clinicopathological features, histomorphological features [nuclear criteria, minor diagnostic features, follicles oriented perpendicular to tumor border/capsule (FOPBC)] and molecular alterations in BRAF, NRAS, and KRAS genes were evaluated. FOPBC were significantly more frequently seen in encapsulated tumors with invasion (p = 0.008). The nuclear features were not associated with the presence of encapsulation and characteristics of tumor border. BRAF mutation was more frequent in infiltrative tumors, while NRAS mutation was more frequent in encapsulated tumors, but the results were not statistically significant (p = 0.917). In conclusion, FOPBC histomorphological feature may be associated with tumor invasion in EFVPTC/NIFTP. Additionally, BRAF/KRAS/NRAS mutation analysis may prevent inadequate treatment in these patients.

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP): a review for clinicians

“…The size of the tumor does not constitute a criterion for the diagnosis of NIFTP (Nikiforov et al 2018), although some cases require greater care and time-consuming evaluation to ensure the absence of excluding findings. Reviewing 250 patients with subcentimeter NIFTP from nine studies (Thompson 2016, Can et al 2017, Hahn et al 2017, Kwon et al 2017, Johnson & Sadow 2018, Mainthia et al 2018, Rosario 2018c, Shafique et al 2018, Xu et al 2018, without associated PTC, we found only two patients with micrometastases <2 mm in a single lymph node in the central compartment, none with distant metastases and no case of recurrence. In addition, reviewing 265 patients with NIFTP ≥4 cm (Thompson 2016, Golding et al 2017, Kwon et al 2017, Rosario 2017b, Xu et al 2017a, Chereau et al 2019, Kim et al 2018b, Mainthia et al 2018, Parente et al 2018, excluding cases with associated PTC, we did not identify any patients with lymph node metastases (LNM), only one with pulmonary metastases and no case of recurrence.…”

Thyroid Papillary Carcinoma and Noninvasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features (NIFTP)

“…One of these subjects had under gone in complete excision and non invasive nature of tumor was questionable in other patient. In general, data suggest that the rate of negative result is very low in the absence of invasion of this lesion [12][13][14][15][16][17][18].…”