Incidental Cystadenomas of the Seminal Vesicle: An Institutional Series.

Cystadenoma of the seminal vesicle is a benign epithelial tumor composed of variably sized cysts, lined by bland epithelial cells, and surrounded by fibromuscular stroma. Considered rare and mostly described in case reports, affected patients are frequently described as presenting with obstructive urinary symptoms due to mass effect. Nonetheless, anecdotally, we have seen these tumors present more frequently as smaller, incidental lesions. To study this phenomenon, we reviewed our institutional experience with such lesions, identifying 7 incidental cystadenomas involving the seminal vesicles, 2 of which involved the seminal vesicles bilaterally, including 1 also with a concomitant cystadenoma of the prostate. Two were apparent at preoperative multiparametric magnetic resonance imaging. The patients' ages ranged from 43 to 72 years; all were incidental findings, 0.5 to 1.8 cm at prostatectomy or cystoprostatectomy performed for conventional prostatic or urothelial carcinoma. Focal epithelial atypia regarded as low-grade dysplasia was apparent in one; all expressed nuclear PAX8. In summary, cystadenomas of the seminal vesicle may be under-recognized as smaller, incidental forms. Greater experience will be needed to assess their relative prevalence and significance of epithelial atypia.