In:
Histopathology, Wiley, Vol. 72, No. 4 ( 2018-03), p. 648-661
Abstract:
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 . Methods and results This study was performed on 177 consecutive FVPTC s 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 V600E was found in 12.2% (non‐invasive) and 11.8% (invasive) of encapsulated FVPTC s, and in 34.6% of infiltrative FVPTC s ( P = 0.001). Mutation in encapsulated FVPTC s was limited to cases with rare or abortive papillae. RET – PTC 1 and RET – PTC 3 rearrangements were present (11.5%) only in infiltrative FVPTC s. In contrast, NRAS , HRAS and KRAS mutations were observed more often in encapsulated FVPTC s (48.6% in non‐invasive and 66.7% in invasive) than in infiltrative FVPTC s (15.4%) ( P 〈 0.001). Preoperative cytological examination did not distinguish between non‐invasive and invasive encapsulated FVPTC s, whereas infiltrative FVPTC was more likely to be Bethesda class V/ VI than the encapsulated type (60.4% versus 38.1%; P = 0.01). Conclusions There were no differences in clinicopathological or molecular profiles between non‐invasive and invasive encapsulated FVPTC s, 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.
Type of Medium:
Online Resource
ISSN:
0309-0167
,
1365-2559
DOI:
10.1111/his.2018.72.issue-4
Language:
English
Publisher:
Wiley
Publication Date:
2018
detail.hit.zdb_id:
2006447-0
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