[926] The Novel Immunohistochemical p75/p63 Antibody Cocktail Is a Reliable Basal Cell Marker in Prostatic Core Needle Biopsies

SM Moran, O O'Brien, F O'Connell, D McCrae, TJ Browne. Cork University Hospital, Cork, Ireland

Background: Nerve growth Factor receptor (NGFR/p75NTR ) is a cell surface receptor glycoprotein with tumour suppressor functions and roles in regulation of cell growth and proliferation. Its expression in breast myoepithelial cells and prostate basal cells has been previously established. The aim of this study was to develop a novel p75/p63 antibody cocktail (p75 cocktail), to evaluate it as a basal cell marker in benign and malignant prostatic core needle biopsies (CNB) and to compare this to the p63/34BE12 cocktail.
Design: A novel immunohistochemical (IHC) p75 cocktail was developed and optimized in our laboratory. With institutional approval 56 sequential prostatic CNB were selected from surgical pathology files (28 benign, 28 malignant). All H&E slides were reviewed and diagnosis confirmed. Paraffin sections were stained with the newly developed p75/P63 and previously validated p63/ 34BE12 cocktails. A scoring system incorporating distribution and intensity in basal cells, luminal cells and stromal cells was established. Distribution and intensity were graded on 4 tier systems (Distribution: 1<5%, 2= 5-25%, 3=25-50%, 4>50%, cells positive. Intensity: 0=negative, 1=weak, 2=moderate, 3=strong). Each case was scored independently by two pathologists.
Results: P75 cocktail staining distribution and intensity: 100% of malignant CNB showed absent basal cell staining. All benign CNB showed positivity with excellent distribution (92.3% score 4/4, 7.7% score 3/4). Staining intensity was at least moderate (11.5%) with the majority of cases showing strong (88.5%) intensity. There was no statisitically significant difference observed for either intensity or distribution in basal, luminal or stromal cells when compared to the p63/34BE12 cocktail. p75 cocktail also highlighted nerves aiding identification of perineural invasion (PNI).
Conclusions: A novel IHC antibody cocktail p75/p63 was developed and shown to be a reliable basal cell marker in the evaluation of both malignant and benign prostate CNB specimens. An added advantage of this cocktail is that it highlights nerves aiding evaluation of PNI.
Category: Genitourinary (including renal tumors)

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 108, Tuesday Afternoon


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