Discordance of HER2 Positive Classic Invasive Lobular Carcinoma Between IHC/FISH and Oncotype DX: A Case Report and Literature Review

Discordance of HER2 Positive Classic Invasive Lobular Carcinoma Between IHC/FISH and Oncotype DX: A Case Report and Literature Review

Author Info

Corresponding Author
Khin Su Mon
Department of Pathology and Laboratory Medicine, Loyola University Medical Center, Maywood, Illinois, USA

A B S T R A C T

The classical-type of invasive lobular carcinoma (ILC) usually expresses high levels of estrogen receptor (ER) and progesterone receptor (PR) and does not over-express human epidermal growth factor receptor 2 (HER2) and has a low level of expression of the proliferative marker. Their prognosis is comparable with those of histologic grade 1-2 invasive ductal carcinoma (IDC). HER2 status is prognostically significant and has a huge impact on clinical management; thus, its correct testing and evaluation are critical. Discordant results for HER2 between immunohistochemistry (IHC)/fluorescence in situ hybridization (FISH) and Oncotype DX (ODX) testing can be occasionally seen and cause confusion among clinicians. Here, we present a case of classical ILC (cILC), which was HER2 positive by IHC/FISH but negative by ODX. We also review relevant literature and provide a possible explanation for this discordancy and suggestions on how to approach the discordant results and guide the clinical management.

Article Info

Article Type
Case Report and Review of the Literature
Publication history
Received: Wed 18, May 2022
Accepted: Thu 02, Jun 2022
Published: Tue 14, Jun 2022
Copyright
© 2021 Khin Su Mon. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Hosting by Science Repository.
DOI: 10.31487/j.SCR.2022.06.01