[1001] Intraepithelial Spread of Prostate Carcinoma in Cases of Seminal Vesicle Invasion (Stage pT3b). Retrospective Analysis of Non-Recognized Pattern of Tumor Spread in Seminal Vesicle

Sergio Pina-Oviedo, Anna Kristiansen, Lars Egevad, Mukul Divatia, Steven S Shen, Jae Y Ro. Methodist Hospital, Houston, TX; Karolinska University Hospital, Stockholm, Sweden

Background: Seminal vesicle (SV) invasion by prostate carcinoma is designated stage pT3b in the 2010 TNM classification. Three ways of SV invasion may occur: 1) through the ejaculatory duct, 2) direct invasion into SV soft tissue and wall, and 3) discontinuous metastasis. Intraepithelial spread into the SV epithelium by prostate cancer has not been recognized since SV epithelium may mimic or mask prostate carcinoma cells. Careful evaluation with HE stains and comparison with specific immunohistochemical markers for prostate cancer cells (PSA) and SV epithelium (PAX8) may be helpful to identify this feature. We reviewed 111 cases of stage T3b prostate cancer in order to identify SV intraepithelial spread by prostate cancer cells.
Design: A total of 111 cases (51 cases retrieved from The Methodist Hospital and 60 from the Karolinska University Hospital) with prostate carcinoma, stage pT3b were evaluated for the presence of intraepithelial spread. Immunohistochemistry for PSA and PAX8 was performed to confirm this finding (available only for TMH cases). Clinicopathologic features including patient's age, Gleason score, and extraprostatic extension were also studied.
Results: Fourteen of 111 cases (12.6%) of prostate carcinoma stage pT3b featured intraepithelial SV extension. Further evaluation with PSA and PAX8 immunohistochemistry confirmed this finding. The age range in the 14 cases was 52 to 68 years old (median 61); Gleason score were 7, 8 and 9 in 2, 5 and 7 cases, respectively. Concurrent extraprostatic extension (stage pT3a) was present in all 14 specimens. No difference in age or Gleason score was found between cases with and without intraepithelial SV involvement.
Conclusions: Intraepithelial spread of prostate carcinoma is present in up to 12.6% of prostates with stage pT3b. Recognition of this feature is difficult because of the overlapping cytologic features between intraepithelial prostate cancer cells and SV epithelium. Careful evaluation of SV is important and hence, when mucosal involvement by prostate cancer is suspected in HE stains, PSA and PAX8 immunohistochemistry may confirm this feature. This hitherto unreported condition may serve to identify another subset of cases with extraprostatic SV involvement, thus impacting tumor staging. The significance of intraepithelial SV spread awaits further study.
Category: Genitourinary (including renal tumors)

Monday, March 4, 2013 1:00 PM

Poster Session II # 167, Monday Afternoon

 

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