Cytoplasmic Her2/neu Immunohistochemical Staining in Breast Cancer; From a Molecular Point of View.

Akbar Safaei,Ahmad Monabati,Mehdi Montazer,Maral Mokhtar

doi:10.30699/ijp.2019.76630.1732

Akbar Safaei, Ahmad Monabati + Show 2 more

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https://doi.org/10.30699/ijp.2019.76630.1732

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Abstract

The most widely used guideline for the breast cancer biomarker assessment and reporting (the 2013 ASCO/CAP guideline) does not state the unusual occurrence of cytoplasmic Her2/neu staining (1, 2). We recently encountered a T2N1Mx ductal adeno-carcinoma which consisted of two dissimilar tumor cell populations. The more prominent population (75% of tumor cells) was made up of sheets of neuroendocrine-like cells (NEL) and the other tumor cell population had a usual adenocarcinomatous histomorphology (UAC) (Fig. 1A). The NEL was ER+ (clone 073), PgR-(clone 636), 40% ki67 with distinct dot-like cytoplasmic Her2 staining (clone CB11) which is considered as negative regarding the current guidelines. The UAC was ER+, PgR+, 20% ki67, and Her2 negative (Fig. 1A-C). Moreover, NEL did not react with either chromogranin or synaptophysin, but it expressed neuron-specific enolase (NSE). Dual color Her2/neu chromogenic in situ hybridization probes (chromogenic ISH) established that both components were not amplified for this oncoprotein gene (Fig. 1D).

Highlights

We recently encountered a T2N1Mx ductal adenocarcinoma which consisted of two dissimilar tumor cell populations
The more prominent population (75% of tumor cells) was made up of sheets of neuroendocrine-like cells (NEL) and the other tumor cell population had a usual adenocarcinomatous histomorphology (UAC) (Fig. 1A)
Few papers have previously noted cytoplasmic Her2 staining. They have found, as we did, that this pattern was not associated with the Her2 gene amplification or high Her2 mRNA levels, and some of them attributed it to the artifactual staining by the routinely employed CB11 Her2 clone [1]

Summary

Introduction

We recently encountered a T2N1Mx ductal adenocarcinoma which consisted of two dissimilar tumor cell populations. 1.Department of Hematopathology, Molecular Pathology and Cytogenetics, Shiraz University of Medical Sciences, Shiraz, Iran Dear Editor, The most widely used guideline for the breast cancer biomarker assessment and reporting (the 2013 ASCO/CAP guideline) does not state the unusual occurrence of cytoplasmic Her2/neu staining [1, 2].

Results

Conclusion