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Increased expression of α-methylacyl-coenzyme A racemase (AMACR; p504s) and p16 in distal hyperplastic polyps

Nimet Dayi1, Hideo A Baba2, Kurt W Schmid2 and Klaus J Schmitz23*

Author affiliations

1 St. Barbara-Hospital, Barbarastrasse 1, 45964 Gladbeck, Germany

2 Institute of Pathology and Neuropathology, University of Duisburg-Essen, Hufelandstrasse 55, 45122 Essen, Germany

3 Institute of Pathology Recklinghausen, Mühlenstrasse 31, 45659 Recklinghausen, Germany

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Citation and License

Diagnostic Pathology 2013, 8:178  doi:10.1186/1746-1596-8-178

Published: 23 October 2013

Abstract

Background

Hyperplastic polyps (HP) and sessile serrated adenomas (SSA) share morphological similarities. In this immunohistochemical study we chose a panel of potential relevant and promising biomarkers including α-methylacyl-coenzyme A racemase (AMACR; p504s), which is involved in the degradation of branched chained fatty acids derivates, and analysed a cohort of HPs and SSAs in order to identify different immunophenotypes in relation to lesion localisation.

Methods

154 specimen were carefully selected and a micro tissue array (TMA) was constructed. Immunohistochemistry of p16Ink4a, Ki67, α-methylacyl-coenzyme A racemase (AMACR; p504s), BRAF, CK 20, MLH1 and β-catenin was performed and and immunoexpression was compared among proximal and distal HPs as well as SSAs.

Results

None of the markers revealed a differential expression among HPs and SSAs. However, the study demonstrates a significant overexpression of AMACR (p = 0.004) and p16Ink4a (p = 0.028) in distal HPs compared to proximal HPs. In addition AMACR overexpression was associated with increased p16Ink4a immunoexpression (p < 0.001).

Conclusions

In this study we describe differential AMACR and p16Ink4a in HPs in relation to their localisation. Distal HPs were characterized by AMACR and p16Ink4a overexpression in contrast to proximal HPs, although morphological identically. Thus AMACR overexpression points towards a pathobiological relevance of the protein in distal HPs. In context of recently published data this suggest distal HPs as potential precursor lesions of certain adenoma subtypes. However, at this point of time this finding remains speculative and needs to be confirmed by further studies.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1836116001066768 webcite

Keywords:
AMACR; p16Ink4a; Hyperplastic polyp; Sessile serrated adenoma