Comparison of clinicopathological features in patients with noninvasive follicular thyroid neoplasm with papillary-like nuclear features and follicular variant papillary thyroid cancer.

INTRODUCTION: Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) is a newly defined entity accepted as a tumor precursor. OBJECTIVES: We aimed to examine the features of patients diagnosed with follicular variant papillary thyroid carcinoma (FVPTC), which are classified as NIFTP in the recent classification. This study compares clinical, radiological, histopathological, and molecular featur es of NIFTP and FVPTC. PATIENTS AND METHODS: A total of 247 patients with FVPTC were retrospectively examined and pathology specimens were reviewed. RESULTS: Patients were divided into 2 groups (NIFTP group: 107 patients; FVPTC group: 140 patients). There was a difference in terms of the percentage of pathologic nodules with irregular borders detected on preoperative neck ultrasonography (NIFTP group: 6.5%, FVPTC group: 15.7%; P = 0.02). Central lymph node dissection specimens of 50 patients in the NIFTP group were normal, while 4 of 70 patients (5.7%) in the FVPTC group had lymph node metastasis (P = 0.14). In addition, multivariable analysis (binary logistic regression) showed that FVPTC was positively associated only with irregular borders and extrathyroidal extensions (P = 0.02 and P <0.001, respectively). CONCLUSIONS: We suggest that patients diagnosed with NIFTP according to the new classification are considered lowrisk, and margin characteristics of the nodule detected on preoperative ultrasonography may be helpful in the differential diagnosis.

Comparison of clinicopathological features in incidental and nonincidental papillary thyroid carcinomas in 308 patients.

Incidental papillary thyroid carcinomas (IPTCs) consist of a significant portion of increasing incidence in papillary thyroid carcinomas. This study investigated the clinicopathological features of IPTCs from different perspectives and by comparing nonincidental PTCs (NIPTCs) in patients who underwent total thyroidectomy and lymph node dissection. Basic results were as follows. IPTC was present in 27.9% of 308 patients. IPTCs were significantly accompanied by lymphocytic thyroiditis (LT), particularly, multinodular hyperplasia (MNH). IPTCs were more common in older patients (51.3 years vs. 47.2 years) and in female patients. IPTCs significantly differed from NIPTCs in terms of smaller tumour size, lymphatic vessel invasion (2.6% vs. 97.4%), extrathyroidal extension (4.3% vs. 95.7%), lymph node metastasis (3.6% vs. 96.4%), multifocality (21.2% vs. 78.8%), bilaterality (5.3% vs. 94.7%), and BRAFV600 mutation (6.7% vs. 93.3%). Older age, bilaterality, encapsulation, and radioactive iodine (RAI) were significantly more common in IPTCs > 5 mm than in those ≤ 5 mm. In conclusion, IPTCs are more commonly associated with LT and MNH. IPTCs may have a more favourable prognosis than NIPTCs, and tumour size > 5 mm may predict bilaterality and need for RAI. Nevertheless, the patient-based clinical approach in IPTCs may have benefits in the management of IPTCs.