Prostate-specific antigen expression and lipochrome pigment granules in the differential diagnosis of prostatic adenocarcinoma versus seminal vesicle-ejaculatory duct epithelium

Background.-Lipochrome pigment granules (LPGs) and prostate-specific antige n (PSA) localization have been cited as helpful adjuncts in differentiating atypical histologic patterns of seminal vesicle-ejaculatory duct (SVED) fr om prostatic adenocarcinoma. However, LPGs have been described in both beni gn and neoplastic prostatic acini, and PSA expression within the intraprost atic SVED has not been fully explored. Design.-Fifty radical prostatectomy specimens were studied for LPGs and 9 c ases for PSA expression. Results.-Two morphologic types of LPGs (type 1 and type 2) were observed. T he reproducibility in classifying LPGs was evaluated by kappa statistics, w hich demonstrated a strong agreement between 4 observers. Type 1 was restri cted to SVED in all 50 specimens. Type 2 was subclassified into 2A and 2B. Type 2 LPGs were observed in prostatic acini of different zones, high-grade prostatic intraepithelial neoplasia, prostatic adenocarcinoma, and occasio nally with type 1 LPG in SVED. Focal reactivity for PSA in the distal porti on of SVED near urethra was noted in 1 of 9 cases. Conclusion.-Awareness about morphologic differences between the 2 types of LPGs could help to avoid a potential diagnostic pitfall of misinterpreting SVED epithelium for adenocarcinoma. Caution is recommended in interpreting PSA expression, since rare focal PSA reactivity was observed in the distal SVED.