[859] The Distribution of PAX-2 Immunoreactivity in the Prostate Gland, Seminal Vesicle, and Ejaculatory Ducts: Comparison to Prostatic Adenocarcinoma and Implications for Diagnostic Use

CM Quick, N Gokden, AR Sangoi, JK McKenney. UAMS, Little Rock, AR; Stanford, Stanford, CA

Background: PAX-2 is a homeogene strongly expressed during development of the genitourinary tract. Expression of PAX-2 by immunohistochemistry has been studied mainly in renal epithelial and ovarian neoplasms with little attention to the male lower genitourinary tract. We studied PAX-2 expression in epithelium of normal seminal vesicle, normal ejaculatory duct, normal prostatic secretory epithelium, and prostatic adenocarcinoma to define its immunoreactivity pattern throughout the prostate gland and address its potential diagnostic role in the discrimination of seminal vesicle/ejaculatory duct from prostatic adenocarcinoma.
Design: Prostatectomy specimens from 12 patients were reviewed to identify seminal vesicle, ejaculatory duct, periurethral glands, benign prostatic glands, and prostatic acinar adenocarcinoma. 2 tissue microarray (TMA) slides representing 15 seminal vesicles and 45 prostatic adenocarcinomas were also used. Immumnohistochemistry for PAX-2 (Z-RX2; Zymed, San Francisco, CA) was performed on each block.
Results: A total of 32 blocks from the 12 prostatectomies were evaluated. In these whole tissue sections, nuclear reactivity for PAX-2 was identified in 12/12 (100%) of the seminal vesicle epithelium, 9/10 (90%) ejaculatory duct epithelium, focally in 1/12 (8.3%) normal prostate secretory epithelium, 0/12 prostatic adenocarcinoma, and 0/6 high grade prostatic intraepithelial neoplasia. The intensity of nuclear PAX-2 reactivity was much stronger in seminal vesicle epithelium compared to the ejaculatory duct. The focal nuclear reactivity in normal prostatic secretory epithelium of one case was within the central zone. In the TMA sections, 15 additional seminal vesicles showed strong nuclear reactivity for PAX-2, while the 45 additional prostatic adenocarcinomas were all negative.
Conclusions: PAX-2 shows strong nuclear reactivity in seminal vesicle and ejaculatory duct epithelium, compatible with origin from the Wolffian duct. It appears to be a useful adjunctive immunohistochemical marker in the distinction of seminal vesicle/ejaculatory duct epithelium from prostatic adenocarcinoma that may be useful in difficult biopsies.
Category: Genitourinary (including renal tumors)

Tuesday, March 10, 2009 1:00 PM

Poster Session IV # 123, Tuesday Afternoon