[958] Diagnostic Utility of a Comprehensive Immunohistochemical Panel To Differentiate High Grade Urothelial Carcinoma (UCa) from Prostatic Adenocarcinoma (PCa)

Sambit K Mohanty, Daniel Luthringer, Allen M Gown, Manju Aron, Mahul B Amin. Cedars-Sinai Medical Center, Los Angeles, CA; PhenoPath Laboratories, Seattle, WA

Background: The distinction between high-grade UCa and high-grade PCa in transurethral resection (TUR) specimens particularly from the bladder neck can be extremely challenging. The diagnostic difficulty is compounded by cases felt clinically to be PCa which are immunohistochemically (IHC) negative for prostate specific antigen (PSA). Accurate characterization is necessary as treatment modalities are significantly different (cystoprostatectomy/chemotherapy for UCa and hormonal/radiation therapy for PCa). The aim of this study was to evaluate the potential appropriateness of a broad immunohistochemical panel in differentiating high-grade UCa from high grade PCa.
Design: With IRB approval, the institutional pathology database was searched for high grade UCa and high-grade PCa on TUR specimens. Cases were then subjected to a panel of eleven established and emerging IHC markers including urothelial-associated markers: GATA3, S100p, IMP3, p63, CK7, CK20, CK5/6, uroplakin III, and prostate-associated markers: PSA, prostate specific membrane antigen (PSMA) and androgen receptor (AR). The staining results were recorded in semiquantitative fashion as estimated percentage of tumor cells immunoreactive with the antibodies (0: negative, 1+: 1-25, 2+: 26-50, 3+: 51-100% and intensity as weak, moderate and strong). IMP3 staining was considered positive when 10% of neoplastic cells were immunolabeled by the stain.
Results: 14 cases of high-grade UCa and 12 cases of high-grade PCa were identified. The details of key IHC results are summarized in the table as percentage positivity in the tumors. CK7, IMP3, CK5/6 and Uroplakin in UCa was 93, 71, 57 and 14% vs.17, 17, 0 and 0% in PCa.


Conclusions: A majority of high-grade PCa are PSA negative requiring a panel of IHC markers to confirm PCa and in its distinction from UCa. Urothelial lineage-associated markers, GATA3 and S100p, are relatively sensitive and specific for urothelial differentiation in the context of the differential diagnosis of UCa and PCa. A panel comprising of urothelial-associated markers (GATA3, S100p and p63 or CK20) and prostate-associated markers (PSMA, PSA and AR) has diagnostic utility in the therapeutically critical distinction of high-grade PCa from UCa.
Category: Genitourinary (including renal tumors)

Tuesday, March 20, 2012 8:45 AM

Platform Session: Section A, Tuesday Morning


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