Classical and Follicular Variant Papillary Thyroid Carcinoma: Comparison of Clinical, Ultrasonographical, Cytological, and Histopathological Features in 444 Patients

Abstract

Follicular variant papillary thyroid carcinoma (FVPTC) is the most common variant of papillary thyroid carcinoma (PTC) after classical PTC (CPTC). In this study, we aimed to compare functional status, ultrasonographical features, cytological results, and histopathological characteristics of patients with CPTC and FVPTC. Preoperative thyroid functions, thyroid autoantibodies, ultrasonographical features, cytology, and histopathology results of 354 (79.9%) CPTC and 90 (20.3%) FVPTC patients were reviewed retrospectively. Sex distribution, mean age, thyroid autoantibody positivity, and thyroid dysfunctions were similar in two groups. Among 320 patients with preoperative ultrasonography (US) findings, a hypoechoic halo was observed more frequently (p=0.003), and marginal irregularity was observed less commonly (p=0.024) in FVPTC lesions. In CPTC, rate of malignant cytology (p=0.001), and in FVPTC, rate of suspicious cytology (p<0.001) were significantly higher. Histopathologically, mean tumor diameter was markedly higher in FVPTC compared to CPTC (16.89 ± 13.86 vs 10.64 ± 9.70 mm, p<0.001), while capsular invasion and extrathyroidal spread were significantly lower in patients with FVPTC (p=0.018 and p=0.039, respectively). FVPTC tend to have more benign features in US and less malignant results in cytology. Higher tumor size in FVPTC might be explained by the recognition of clinical importance of these lesions after reaching particular sizes due to benign US features.

Comparison of the clinicopathological behavior of the follicular variant of papillary thyroid carcinoma and classical papillary thyroid carcinoma: A systematic review and meta-analysis

“…The mean tumor size of patients with FV-PTC was larger than that of the patients with C-PTC, which is in agreement with the results of studies by Chang et al (10), Ozdemir et al (17), Burningham et al (19), Jain et al (49) and Kim et al (50). Ozdemir et al (17) and Kim et al (50) also reported that compared to C-PTC, FV-PTC has more benign sonographic features, a lower incidence of a sonographically malignant grade and a lower diagnostic rate of PTC on fine-needle aspiration biopsy (FNAB). Thus, the lower rate of suspicious findings in FV-PTC lesions may have caused evaluation of larger FV-PTC lesions by FNAB, resulting in the detection of these lesions at a later stage.…”

“…Passler et al (12) suggested that there was a significantly higher prevalence of multifocality in patients with FV-PTC compared to patients with C-PTC, but the opposite was reported by Gao et al (31) and Trovisco et al (47). Certain studies reported a higher prevalence of capsular invasion and vascular invasion in the FV-PTC (10,20,51), whereas others did not (17,43,47). Although the majority of the C-PTCs do not have a tumor capsule, patients with C-PTC (28.1%) and patients with FV-PTC (30.2%) showed a similar high prevalence of capsular invasion of tumor in the present meta-analysis.…”

“…Of the remaining 413, 112 full-text studies were deemed relevant and were examined in detail. Eventually, following the application of all the inclusion and exclusion criteria, 36 studies (7,8,10,12,14,16,17,19,20, fulfilled the eligibility criteria. The main features of the eligible studies are summarized in Table I.…”

“…Numerous studies have since investigated the clinical behavior of FV-PTC and the classical type of PTC (C-PTC) and compared the two; however, certain results were contradictory. In different studies, the incidence of aggressive clinical features was identified as higher, similar or lower in FV-PTC compared to C-PTC (5,7,8,10,12,(15)(16)(17)(18)(19)(20).…”

Follicular Variant of Papillary Thyroid Carcinoma: Cytological Indicators of Diagnostic Value

“…Even focal nuclear features of papillary carcinoma thyroid in fine needle aspiration cytology are strongly associated with papillary carcinoma at resection, [12] particularly FVPTC [13]. Higher tumor size and rate of suspicious for malignancy cytology were significantly higher in FVPTC [14]. If we use histologic diagnosis as the gold standard, the sensitivity and specificity of FNAC diagnosis of FVPTC were 42% and 83%, respectively [15].…”