Header

UZH-Logo

Maintenance Infos

Immunohistochemical Assessment of HRAS Q61R Mutations in Breast Adenomyoepitheliomas


Abstract

AIMS

Breast adenomyoepitheliomas (AMEs) are uncommon tumors. Most estrogen receptor (ER)-positive AMEs have mutations in PI3K pathway genes, whereas ER-negative AMEs usually harbor concurrent mutations affecting the HRAS Q61 hotspot and PI3K pathway genes. Here, we sought to determine the sensitivity and specificity of RAS Q61R immunohistochemical (IHC) analysis for detection of HRAS Q61R mutations in AMEs.

METHODS AND RESULTS

26 AME (14 ER-positive, 12 ER-negative) previously subjected to massively parallel sequencing (n=21) or Sanger sequencing (n=5) of the HRAS Q61 hotspot locus were included in this study. All AMEs were subjected to IHC using a monoclonal (SP174) RAS Q61R-specific antibody, in addition to detailed histopathologic analysis. Nine ER-negative AMEs harbored HRAS mutations, including Q61R (n=7) and Q61K (n=2) mutations. 5/7 (71%) AMEs with HRAS Q61R mutations were positive by IHC, whereas none of the AMEs lacking HRAS Q61R mutations (n=17) were immunoreactive. RAS Q61R immunoreactivity was restricted to the myoepithelium in 80% (4/5) of cases, whereas one case displayed immunoreactivity in both the epithelial and myoepithelial components. RAS Q61R IHC-positive AMEs were associated with infiltrative borders (P<0.001), necrosis (P<0.01) and mitotic index in the epithelial (P<0.05) and myoepithelial (P<0.01) components. RAS Q61R IHC assessment did not detect Q61K mutations (0/2).

CONCLUSIONS

IHC analysis of RAS Q61R displays a high specificity (100%) and moderate sensitivity (71%) for detection of HRAS Q61R mutations in breast AMEs, and appears not to detect HRAS Q61K mutations. IHC analysis of RAS Q61R may constitute a useful marker in the diagnostic workup of ER-negative AMEs.

Abstract

AIMS

Breast adenomyoepitheliomas (AMEs) are uncommon tumors. Most estrogen receptor (ER)-positive AMEs have mutations in PI3K pathway genes, whereas ER-negative AMEs usually harbor concurrent mutations affecting the HRAS Q61 hotspot and PI3K pathway genes. Here, we sought to determine the sensitivity and specificity of RAS Q61R immunohistochemical (IHC) analysis for detection of HRAS Q61R mutations in AMEs.

METHODS AND RESULTS

26 AME (14 ER-positive, 12 ER-negative) previously subjected to massively parallel sequencing (n=21) or Sanger sequencing (n=5) of the HRAS Q61 hotspot locus were included in this study. All AMEs were subjected to IHC using a monoclonal (SP174) RAS Q61R-specific antibody, in addition to detailed histopathologic analysis. Nine ER-negative AMEs harbored HRAS mutations, including Q61R (n=7) and Q61K (n=2) mutations. 5/7 (71%) AMEs with HRAS Q61R mutations were positive by IHC, whereas none of the AMEs lacking HRAS Q61R mutations (n=17) were immunoreactive. RAS Q61R immunoreactivity was restricted to the myoepithelium in 80% (4/5) of cases, whereas one case displayed immunoreactivity in both the epithelial and myoepithelial components. RAS Q61R IHC-positive AMEs were associated with infiltrative borders (P<0.001), necrosis (P<0.01) and mitotic index in the epithelial (P<0.05) and myoepithelial (P<0.01) components. RAS Q61R IHC assessment did not detect Q61K mutations (0/2).

CONCLUSIONS

IHC analysis of RAS Q61R displays a high specificity (100%) and moderate sensitivity (71%) for detection of HRAS Q61R mutations in breast AMEs, and appears not to detect HRAS Q61K mutations. IHC analysis of RAS Q61R may constitute a useful marker in the diagnostic workup of ER-negative AMEs.

Statistics

Citations

Dimensions.ai Metrics

Altmetrics

Downloads

1 download since deposited on 07 Feb 2020
1 download since 12 months
Detailed statistics

Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > University Hospital Zurich > Institute of Pathology and Molecular Pathology
Dewey Decimal Classification:610 Medicine & health
Language:English
Date:30 December 2019
Deposited On:07 Feb 2020 10:05
Last Modified:07 Feb 2020 10:06
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:0309-0167
OA Status:Closed
Publisher DOI:https://doi.org/10.1111/his.14057
PubMed ID:31887226

Download

Closed Access: Download allowed only for UZH members