Macrofollicular Variant of Follicular Thyroid Carcinoma: A Rare Underappreciated Pitfall in the Diagnosis of Thyroid Carcinoma.

Details

Serval ID
serval:BIB_3593CD8A9C4E
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Macrofollicular Variant of Follicular Thyroid Carcinoma: A Rare Underappreciated Pitfall in the Diagnosis of Thyroid Carcinoma.
Journal
Thyroid
Author(s)
Bongiovanni M., Sykiotis G.P., La Rosa S., Bisig B., Trimech M., Missiaglia E., Gremaud M., Salvatori Chappuis V., De Vito C., Sciarra A., Foulkes W.D., Pusztaszeri M.
ISSN
1557-9077 (Electronic)
ISSN-L
1050-7256
Publication state
Published
Issued date
01/2020
Peer-reviewed
Oui
Volume
30
Number
1
Pages
72-80
Language
english
Notes
Publication types: Journal Article
Publication Status: ppublish
Abstract
Background:
Follicular-patterned thyroid nodules predominantly composed of macrofollicular structures without nuclear atypia are generally regarded as benign (i.e., hyperplastic nodules or follicular adenomas). In line with this concept, fine-needle aspiration cytology (FNAC) also assigns a benign connotation to the presence of macrofollicular structures, unless thyrocytes present papillary thyroid carcinoma (PTC)-related nuclear features that raise the possibility of a macrofollicular variant of PTC. However, cases showing macrofollicular architecture, capsular invasion, and no PTC features can also be observed.
Methods:
We describe the clinical, cytological, histological, and molecular genetic features of four cases of encapsulated follicular neoplasms that presented histologically with a predominant (>70%) macrofollicular architecture, but which also showed clear signs of capsular invasion, and thus were classified as macrofollicular variant of follicular thyroid carcinoma (MV-FTC).
Results:
Cytologically, macrofollicular structures were identified in all cases, leading to a benign FNAC diagnosis in three of the four cases. Due to increasing nodule size, thyroidectomy was performed in all cases. Histology showed focal and limited capsular invasion, without vascular invasion. Next-generation sequencing (custom 394 gene panel) of each tumor compared with matched normal DNA revealed a total of 7 somatic variants, including dual (likely biallelic) mutations in the DICER1 gene in 2 patients. The clinical outcome was excellent in all cases.
Conclusions:
Similar to the classical minimally invasive follicular thyroid carcinoma, MV-FTC appears to behave indolently. MV-FTC has a high rate of false-negative FNAC results, but MV-FTC is very rare (<0.05% of all thyroidectomies) and apparently has an indolent behavior. Further studies comprising larger series are necessary to better clarify the biology of this diagnostically challenging rare tumor.
Keywords
NGS, PPARG and RET rearrangements, follicular carcinoma, macrofollicular variant, thyroid
Pubmed
Web of science
Create date
11/11/2019 10:52
Last modification date
21/03/2020 7:18
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