[1065] ProExC Is a Reliable Biomarker for High Grade Squamous Intraepithelial Lesion: A Comparative Study with p16 and MIB-1

DL Richards, DR Mody, MR Schwartz, QJ Zhai. The Methodist Hospital, Houston, TX

Background: In the histologic evaluation of possible high grade dysplasia, there are many diagnostic challenges, including atrophy, immature squamous metaplasia, and squamous metaplasia with dysplasia. To resolve these dilemmas, pathologists use immunohistochemical stains such as p16 and MIB-1 to aid their morphologic interpretation. However, in some cases the results of these stains are difficult to interpret. ProEx C, a new biomarker, detects the expression of topoisomerase IIA and minichromosome maintenance protein 2 (markers of an aberrant S-phase). The objective of this study was to evaluate ProEx C with MIB-1 and p16 in cases of cervical and vaginal dysplasia and its mimics.
Design: 44 cervical and vaginal biopsies and hysterectomy specimens including normal (2), HPV effect/low-grade dysplasia (8), high grade dysplasia (7), squamous metaplasia without high grade dysplasia (16), squamous metaplasia with high grade dysplasia (8), and atrophic (3) specimens were immunostained for p16, MIB-1 and ProEx C. The immunostains were interpreted without knowledge of the histologic diagnoses. The stains were interpreted as highlighting the lower one third or less of the thickness of the squamous epithelium (negative for high grade dysplasia), or as highlighting above the lower one third (positive for high grade dysplasia).
Results: The breakdown of positive high grade staining by case type is given below (SM=squamous metaplasia, LGD=low grade dysplasia, HGD=high grade dysplasia):

The sensitivity and specificity for high grade dysplasia were:


Conclusions: The results of our study show that MIB-1 and ProEx C have the highest sensitivity and specificity for separating difficult cases of high grade dysplasia from its mimics. Our study suggests that ProEx C is a comparable marker to MIB-1, and a more sensitive and specific marker for high grade dysplasia than p16.
Category: Gynecologic

Monday, March 9, 2009 1:00 PM

Poster Session II # 136, Monday Afternoon