[853] Diagnostic Utility of Androgen Receptor Expression in Discriminating Poorly Differentiated Urothelial and Prostate Carcinoma

Michelle R Downes, Najla al Daoud, Theodorus H van der Kwast. University Health Network, Toronto, ON, Canada

Background: Pathological separation of poorly differentiated urothelial and prostate carcinoma can be difficult but is imperative due to the impact on patient management. A combination of morphology and prostate specific antigen (PSA), prostatic acid phosphatase (PAP), CK7, CK20 and p63/high molecular weight keratin (HMWK) are usually required to resolve this issue. We retrospectively analysed androgen receptor (AR) immunohistochemistry (IHC) as a means to discriminate high grade tumours of bladder and prostate origin.
Design: A retrospective search (2003-2012) was performed to identify bladder and prostate cases in which AR IHC had been ordered. Of the cases retrieved (n=41), 5 were excluded (2 basal cell carcinomas, 2 pure stromal sarcomas and 1 carcinoma ex- nephrogenic adenoma). Of the eligible cases (n=36), 17 were transurethral resections of bladder (TURBT), 7 transurethral resections of prostate (TURP), 4 bladder biopsies, 4 cystoprostatectomy specimens, 3 prostate biopsies and 1 prostatectomy specimen. Review of the pathology report, H&E and IHC slides was performed.
Results: 7 cases were high grade urothelial carcinoma, 1 poorly differentiated carcinoma with neuroendocrine features, 25 prostate carcinoma and 3 had both prostate and bladder tumours (n=36). In every case of prostate carcinoma, the AR showed diffuse, intense nuclear staining which was not seen in urothelial tumours. Of the additional markers ordered, (CK7, CK20, p63/HMWK, Synaptophysin, Chromogranin, PSA, PAP), varying results were noted. PSA was ordered in 21/25 prostate carcinomas and was either negative or showed weak, focal staining in 14/21. PAP was ordered in 15/25 and was negative or showed weak, focal staining in 5/15. The most consistently useful additional marker was CK7 which was ordered on 5/7 urothelial carcinomas and was positive in 4. It showed weak, focal staining in 4/25 prostate carcinomas.
Conclusions: We conclude that AR expression is perhaps the most appropriate IHC marker to separate poorly differentiated urothelial and prostate carcinoma. PSA and PAP are not consistently expressed in high grade prostate carcinoma and high grade urothelial carcinoma may be negative for CK20, p63/HMWK and occasionally CK7. We advocate the inclusion of AR in the IHC panel of markers to differentiate these tumours.
Category: Genitourinary (including renal tumors)

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 146, Wednesday Afternoon

 

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