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Molecular genotyping of the non‐invasive encapsulated follicular variant of papillary thyroid carcinoma
Author(s) -
Kim Tae Hyuk,
Lee Minju,
Kwon AhYoung,
Choe JunHo,
Kim JungHan,
Kim Jee Soo,
Hahn Soo Yeon,
Shin Jung Hee,
Chung Man Ki,
Son Young Ik,
Ki ChangSeok,
Yim Hyun Sook,
Kim YooLi,
Chung Jae Hoon,
Kim Sun Wook,
Oh Young Lyun
Publication year - 2018
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.13401
Subject(s) - thyroid carcinoma , neuroblastoma ras viral oncogene homolog , kras , hras , medicine , pathology , thyroid neoplasm , malignancy , thyroid , cancer , colorectal cancer
Aims 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.