[956] Prostatic Neoplasia Arising from Ectopic Prostatic Tissue within the Seminal Vesicle: A Report of 3 Cases

BD Robinson, PA Humphrey, JI Epstein. The Johns Hopkins Hospital, Baltimore; Washington U. School of Medicine, St. Louis

Background: Ectopia of benign prostatic glands is a rare occurrence, usually seen in the urethra or urinary bladder. To date, only two cases of benign prostatic tissue within seminal vesicle (SV) have been reported, and no cases of malignancy arising from such tissue in SV have been documented.
Design: Three radical prostatectomy specimens with ectopic prostatic tissue within SV were identified at our institutions.
Results: In 2 cases, portions of the SV epithelium were replace by benign prostatic epithelium. In the 3rd case, there were disorganized benign prostatic glands within the SV muscular wall. The prostatic nature of the ectopic glands was confirmed by positive immunostaining for PSA and PSAP, with negative staining in the surrounding seminal vesicle epithelium. In all three cases, high-grade prostatic intraepithelial neoplasia (HGPIN) was present in the prostatic glands, confirmed by immunostaining for p63 and high molecular weight cytokeratin. In one case, infiltrating prostatic adenocarcinoma, Gleason score 3+3=6, originated from the ectopic HGPIN glands. The invasive carcinoma showed negative basal cell staining and moderate staining for AMACR. In the case with invasive cancer arising from the ectopic prostatic tissue, no infiltrating adenocarcinoma was seen in the sections of prostate adjacent to the SV. The only other foci of adenocarcinoma in this patient were microscopic foci of Gleason 3+3=6 cancer in the mid and apical portions of the prostate, excluding invasion of SV from a cancer at the juncture of prostate and SV. In addition, intraductal spread of carcinoma in this case was not seen. The patient has no evidence of biochemical recurrence 4 years after radical prostatectomy.
Conclusions: Recognition of the potential for prostatic neoplasia to arise from ectopic prostatic tissue is important for proper pathologic staging, as these tumors may behave similar to comparable T2 tumors as opposed to T3b cancers. These findings may be more common than what is reported, as 2 of the cases are recent. Also, HGPIN involving the SV can be easily overlooked, with one of the cases missed at a referring institution. Neoplasia arising in the SV is rare consisting of predominantly case reports of primary adenocarcinoma, sarcoma, and mixed epithelial-stromal tumors. This series expands on the neoplastic processes that can arise in the SV.
Category: Genitourinary (including renal tumors)

Monday, March 22, 2010 1:00 PM

Poster Session II # 116, Monday Afternoon

 

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