Villous Adenoma of the Urachus: A Case with Prostate Specific Antigen Immunoreactivity

Abstract

We report a case of a villous adenoma of the urachus discovered incidentally during suprapubic prostatectomy, and discuss a novel immunohistochemical finding that could be diagnostically useful. CASE REPORT A 68-year-old man underwent simultaneous right ureterolithotomy and suprapubic prostatectomy because of hydronephrosis (due t oa2c mcalculus in the ipsilateral lower ureter) and acute urinary retention due to prostatic enlargement, respectively. During prostatectomy an ovoid cystic mass (not diagnosed before surgery by imaging techniques) was noted in the bladder dome without involvement of the adjacent structures. Partial cystectomy with excision of the mass was performed. Postoperative recovery was uneventful. No recurrence of the tumor was noted at 19 months following excision. Gross examination of the specimen showed a mucus filled cystic structure 8 cm in diameter associated with a portion of bladder wall 5 cm in diameter. The lining of the cyst demonstrated an exophytic papillary area 0.8 cm in diameter, which was clearly separated from the surrounding epithelium. Histological examination revealed a cyst lined by transitional epithelium containing a neoplasm with villoglandular architecture (fig. 1, A). The neoplastic cells displayed slight nuclear stratification and crowding, mild nuclear hyperchromatism and occasional prominent nucleoli, while the tumor cell cytoplasm contained acidic mucin (fig. 1, B). Mitotic figures were rare. In the adjacent smooth muscle there were urachal remnants. Tumor invasion was not observed. The pathological diagnosis was villous adenoma that had developed in a urachal cyst. The neoplastic cells exhibited immunoreactivity for cytokeratin 20 and carcinoembryonic antigen. In addition, there was prostatic specific antigen (PSA) immunostaining in the tumor cells and the epithelium of the urachal remnants (fig. 2). Preoperatively, serum PSA was within normal range, while the prostatic specimen showed benign nodular hyperplasia.