[998] Clinical Follow-Up of 101 Patients with Isolated HGPIN Immunostained for ERG

Daniel H Russell, David Tacha, Albert Dobi, Isabell A Sesterhenn, David McLeod, Shiv Srivastava, Joel T Moncur. Walter Reed National Military Medical Center, Bethesda, MD; Biocare Medical, Concord, CA; Joint Pathology Center, Silver Spring, MD; Uniformed Services University of the Health Sciences, Bethesda, MD

Background: The [9FY] antibody to the ERG oncoprotein is a sensitive surrogate marker for the TMPRSS2-ERG gene fusion in prostate cancer. We assessed the utility of this antibody in patients with isolated high grade prostatic intraepithelial neoplasia (HGPIN).
Design: All available prostate needle biopsy cases with isolated HGPIN from Walter Reed Army Medical Center (3/05-12/10) were stained for ERG (Brown), CK5+p63 (Purple) and P504S (Red) (ERG-4, Biocare Medical). Out of 139 total cases with only HGPIN, 169 slides from 101 cases were available. The number of core biopsies per case with HGPIN averaged 1.7 (range 1-10) out of 12 cores.
Results: Of 101 patients, eight (8%) had ERG+ HGPIN. Each patient had only one focus of HGPIN that was ERG+. Seven of the eight patients had other cores with ERG- HGPIN. Five of the eight patients with ERG+ HGPIN were rebiopsied, with an average time to initial rebiopsy of 12 mos (range 3-43 mos). On initial rebiopsy (12 cores performed), all five patients had HGPIN (range 1-3 cores) without invasive adenocarcinoma. One patient's HGPIN exhibited features consistent with intraductal carcinoma in three cores and was ERG+ in all three cores. The HGPIN in the other four rebiopsied patients (range 1-2 cores/case) was ERG-. One of the five patients with ERG+ HGPIN was rebiopsied a third time (after 30 mos) and had adenocarcinoma. The index tumor in this patient's prostatectomy was ERG-. In the 93 patients with HGPIN that was ERG-, 34 underwent rebiopsy after an average of 15 mos (range 3-60 mos). Eight patients (24%) had adenocarcinoma on rebiopsy. Nine patients (26%) had isolated HGPIN on rebiopsy, and 17 (50%) had benign biopsies.
Conclusions: While the number of patients with ERG+ HGPIN was small, the percentage with invasive adenocarcinoma on initial rebiopsy (0%) was less than the percentage with adenocarcinoma after a diagnosis of ERG- HGPIN (24%). A larger study is needed to further assess the significance of ERG+ HGPIN, but this relatively small study suggests that ERG+ HGPIN is not associated with an increased risk of adenocarcinoma on rebiopsy, compared to patients with ERG- HGPIN. The relatively low frequency of ERG+ HGPIN in the current study likely reflects sampling issues and the focal nature of ERG positivity in HGPIN.
Category: Genitourinary (including renal tumors)

Monday, March 19, 2012 1:00 PM

Poster Session II # 183, Monday Afternoon

 

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