[1029] ERG Expression in Intraductal Carcinoma of the Prostate: Comparison with Adjacent Conventional Acinar Prostatic Adenocarcinoma

Thomas M Schneider, Adeboye O Osunkoya. Emory University School of Medicine, Atlanta, GA

Background: Intraductal carcinoma of the prostate (IDC-P) is a variant of prostatic adenocarcinoma that has not been well characterized from the molecular standpoint. It remains debatable whether IDC-P represents colonization of benign glands by pre-existing conventional acinar prostatic adenocarcinoma, or progression of high grade prostatic intraepithelial neoplasia (PIN). TMPRSS2-ERG is the most common gene fusion in conventional acinar prostatic adenocarcinoma, identified in about 40-70% of cases. In this study we compared the expression of ERG in IDC-P and adjacent conventional acinar prostatic adenocarcinoma.
Design: Thirty one confirmed cases of IDC-P with adjacent conventional acinar prostatic adenocarcinoma with available tissue blocks were identified at our institution. Immunohistochemical stains were performed for ERG using a rabbit anti-ERG monoclonal antibody. The ERG expression in the IDC-P component was compared with that in the adjacent conventional acinar prostatic adenocarcinoma.
Results: Mean patient age was 65 years (range: 48-79 years). The tissue specimens were as follows: 15/31 (48%) cases from needle core biopsies, 6/31 (19%) cases from transurethral resections, 8/31 (26%) cases from radical prostatectomy specimens, and 2/31 (7%) cases from cystoprostatectomy specimens. Positive ERG expression was identified in 11/31 (35%) cases of IDC-P. In all 11/11 (100%) cases with positive ERG expression in the IDC-P component, ERG expression was also positive in the adjacent conventional acinar prostatic adenocarcinoma. In the 20/31 cases with negative ERG expression in the IDC-P component, ERG was also negative in the adjacent conventional acinar prostatic adenocarcinoma.
Conclusions: It is highly conceivable that based on the identical ERG expression (positive or negative) in IDC-P and the adjacent conventional acinar prostatic adenocarcinoma, that IDC-P most likely represents colonization of benign glands by adjacent pre-existing conventional acinar prostatic adenocarcinoma. The decreased frequency of ERG expression in this cohort, however raises the possibility that the adjacent conventional acinar prostatic adenocarcinoma in cases of IDC-P, may have a slightly different pathobiology than conventional prostatic acinar adenocarcinoma not associated with IDC-P.
Category: Genitourinary (including renal tumors)

Monday, March 4, 2013 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 154, Monday Morning

 

Close Window