Division of Endocrinology & Metabolism, Department of Medicine, Thyroid Centre, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
Department of Pathology, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Korea.
Histopathology. 2018 Mar;72(4):648-661. doi: 10.1111/his.13401. Epub 2017 Dec 4.
The non-invasive encapsulated follicular variant of papillary thyroid carcinoma (FVPTC) has been managed as a low-risk malignancy. Recently, a proposal was made to reclassify this tumour type as a premalignant lesion and rename it non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). This study aims to provide the first comprehensive study on molecular genotype-phenotype correlations of encapsulated FVPTC.
This study was performed on 177 consecutive FVPTCs from January 2014 to April 2016. These were classified as non-invasive encapsulated FVPTC (n = 74) invasive encapsulated FVPTC (n = 51), and infiltrative FVPTC (n = 52), according to standard criteria, by two independent pathologists. Genetic alterations and other clinicopathological information were compared. BRAF was found in 12.2% (non-invasive) and 11.8% (invasive) of encapsulated FVPTCs, and in 34.6% of infiltrative FVPTCs (P = 0.001). Mutation in encapsulated FVPTCs was limited to cases with rare or abortive papillae. RET-PTC1 and RET-PTC3 rearrangements were present (11.5%) only in infiltrative FVPTCs. In contrast, NRAS, HRAS and KRAS mutations were observed more often in encapsulated FVPTCs (48.6% in non-invasive and 66.7% in invasive) than in infiltrative FVPTCs (15.4%) (P < 0.001). Preoperative cytological examination did not distinguish between non-invasive and invasive encapsulated FVPTCs, whereas infiltrative FVPTC was more likely to be Bethesda class V/VI than the encapsulated type (60.4% versus 38.1%; P = 0.01).
There were no differences in clinicopathological or molecular profiles between non-invasive and invasive encapsulated FVPTCs, except in vascular and capsular invasion. Therefore, the diagnosis of NIFTP, like that of follicular adenoma, may require surgical resection and exclusion of those tumours with any papillae.
非侵袭性包裹滤泡型甲状腺乳头状癌（FVPTC）一直被视为低风险恶性肿瘤。最近，有人提议将这种肿瘤类型重新归类为癌前病变，并将其命名为非侵袭性滤泡性甲状腺肿瘤伴乳头状核特征（NIFTP）。本研究旨在首次对包裹性 FVPTC 的分子基因型-表型相关性进行全面研究。
本研究于 2014 年 1 月至 2016 年 4 月连续对 177 例 FVPTC 患者进行研究。根据标准标准，由两名独立病理学家将其分为非侵袭性包裹性 FVPTC（n = 74）、侵袭性包裹性 FVPTC（n = 51）和浸润性 FVPTC（n = 52）。比较了基因改变和其他临床病理信息。在包裹性 FVPTC 中，BRAF 发现率为 12.2%（非侵袭性）和 11.8%（侵袭性），在浸润性 FVPTC 中发现率为 34.6%（P = 0.001）。在包裹性 FVPTC 中，突变仅局限于罕见或中途停止的乳头中。RET-PTC1 和 RET-PTC3 重排仅见于浸润性 FVPTC（11.5%）。相比之下，NRAS、HRAS 和 KRAS 突变在包裹性 FVPTC 中更为常见（非侵袭性为 48.6%，侵袭性为 66.7%），而在浸润性 FVPTC 中较为少见（15.4%）（P < 0.001）。术前细胞学检查无法区分非侵袭性和侵袭性包裹性 FVPTC，而浸润性 FVPTC 更有可能为 Bethesda 分类 V/VI 型，而非包裹性类型（60.4%比 38.1%；P = 0.01）。
除血管和包膜侵犯外，非侵袭性和侵袭性包裹性 FVPTC 在临床病理或分子特征方面无差异。因此，像滤泡性腺瘤一样，NIFTP 的诊断可能需要手术切除并排除任何有乳头的肿瘤。
