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Diagn Cytopathol. 2018 May;46(5):369-377. doi: 10.1002/dc.23915. Epub 2018 Mar 8.

Cancer risk and clinicopathological characteristics of thyroid nodules harboring thyroid-stimulating hormone receptor gene mutations.

Author information

1
Division of Endocrinology and Metabolism, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
2
Division of Translational Pathology, Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey.
3
Department of Internal Medicine, University of Washington, Seattle, Washington.
4
Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania.
5
Division of Endocrinology and Metabolism, NYU School of Medicine, NYU Langone Medical Center, New York, New York.

Abstract

BACKGROUND:

Thyroid-stimulating hormone receptor (TSHR) gene mutations play a critical role in thyroid cell proliferation and function. They are found in 20%-82% of hyperfunctioning nodules, hyperfunctioning follicular thyroid cancers (FTC), and papillary thyroid cancers (PTC). The diagnostic importance of TSHR mutation testing in fine needle aspiration (FNA) specimens remains unstudied.

METHODS:

To examine the association of TSHR mutations with the functional status and surgical outcomes of thyroid nodules, we evaluated 703 consecutive thyroid FNA samples with indeterminate cytology for TSHR mutations using next-generation sequencing. Testing for EZH1 mutations was performed in selected cases. The molecular diagnostic testing was done as part of standard of care treatment, and did not require informed consent.

RESULTS:

TSHR mutations were detected in 31 (4.4%) nodules and were located in exons 281-640, with codon 486 being the most common. Allelic frequency ranged from 3% to 45%. Of 16 cases (12 benign, 3 FTC, 1 PTC) with surgical correlation, 15 had solitary TSHR mutations and 1 PTC had comutation with BRAF V600E. Hyperthyroidism was confirmed in all 3 FTC (2 overt, 1 subclinical). Of 5 nodules with solitary TSHR mutations detected at high allelic frequency, 3 (60%) were FTC. Those at low allelic frequency (3%-22%) were benign. EZH1 mutations were detected in 2 of 4 TSHR-mutant malignant nodules and neither of 2 benign nodules.

CONCLUSION:

We report that TSHR mutations occur in ∼5% thyroid nodules in a large consecutive series with indeterminate cytology. TSHR mutations may be associated with an increased cancer risk when present at high allelic frequency, even when the nodule is hyperfunctioning. Benign nodules were however most strongly correlated with TSHR mutations at low allelic frequency.

KEYWORDS:

TSHR gene mutations; allelic frequency of TSHR gene mutations; cancer risks and TSHR mutation; follicular thyroid cancer and TSHR; thyroid nodules

PMID:
29516685
DOI:
10.1002/dc.23915
[Indexed for MEDLINE]

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