[770] Utility of p63 and HMWCK in the Distinction between Urothelial Carcinoma with Prostatic Stromal Invasion and Urothelial Carcinoma with Colonization of Prostatic Ducts and Acini.

Elizabeth C Chastain, Irma V Oliva, Adeboye O Osunkoya. Emory University School of Medicine, Atlanta

Background: Urothelial carcinoma with prostatic stromal invasion (UCaPSI) is associated with poor clinical outcome, especially if the tumor arises from the urinary bladder (pT4a). However, patients with urothelial carcinoma with colonization of prostatic ducts and acini (UCaCPDA) without invasion (pTis) have a much better clinical outcome. Unfortunately, the distinction could be challenging in some cases on H&E, and is a relatively common reason for urologic pathology consultation. To our knowledge, no study has been published to date specifically addressing the utility of immunohistochemical stains in the distinction between UCaPSA and UCaCPDA. In this study, we sought to determine the utility of p63 and HMWCK in this setting.
Design: A search was made through the surgical pathology and consultation files at our institution for cases of UCaPSI. Only cases with foci of adjacent UCaCPDA were selected for analysis. Immunohistochemical stains for p63 and HMWCK were performed. In all cases, adjacent benign prostatic glands were used as internal controls for the presence of basal cells. Intensity of p63 and HMWCK expression in UCa, which may impact the interpretation of the immunohistochemical stains, was also analyzed.
Results: 41 cases of UCaPSI with adjacent UCaCPDA were identified. All cases showed strong expression of p63 and HMWCK in the basal cells. 27/41 cases (66%) of UCa showed no or weak expression of HMWCK in the tumor cells. 14/41 cases (34%) of UCa showed strong expression of HMWCK in the tumor cells. 30/41 cases (73%) of UCa showed strong expression of p63 in tumor cells. 11/41 cases (27%) of UCa showed no or weak expression of p63 in tumor cells. In the 27/41 cases (66%) which showed no or weak expression of HMWCK, the staining of basal cells in UCaCPDA distinguished it from UCaPSI. However, in the cases in which the tumor stains positively for HMWCK, the distinction was not readily evident. In the 11/43 cases (27%) of UCa which showed no to weak expression of p63 in tumor cells, the staining of basal cells in the UCaCPDA distinguished it from UCaPSI. In the cases in which the tumor stains positively for p63, larger malignant cells and smaller benign basal cells were easily distinguishable.
Conclusions: In difficult cases, p63 and HMWCK which are readily available markers can be utilized in the distinction between UCaPSI and UCaCPDA. These markers especially when used in combination may be utilized in radical cystoprostatectomy, transurethral resection of prostate, and needle core biopsy specimens.
Category: Genitourinary (including renal tumors)

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 175, Tuesday Morning

 

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