Inverted papillomas of the prostatic urethra.

Inverted papillomas of the genitourinary tract are uncommon benign neoplasms usually occurring in the urinary bladder and less frequently in the upper urinary tract. To date, there are scant data and no comprehensive studies of inverted papilloma originating in the prostatic urethra. We identified 21 cases and evaluated their demographic, clinical, and histopathologic features. Patients had a mean age of 65.1 years (range: 30 to 89 y), with 10/21 (47.6%) presenting with gross hematuria (n = 8) or irritative symptoms (n = 2) related to the inverted papilloma and 11/21 (52.4%) detected incidentally during work-up/treatment of prostate cancer (n = 6) or benign prostatic hypertrophy (BPH) (n = 5). Fourteen cystoscopically evaluated lesions measured 0.1 to 2.0 cm, and were described as polypoid (n = 9), papillary (n = 4), or an enlarged median lobe (n = 1). Lesions were diagnosed on transurethral resection (n = 8), biopsy/polypectomy targeted to the lesion (n = 6), radical prostatectomy for prostate cancer (n = 4), or biopsy unrelated to the lesion (n = 3). Histologically, 14/21 cases (67%) displayed classic inverted papilloma architecture. The remaining cases showed foci of squamous metaplasia with moderate atypia (n = 4), rare true papillary fronds in a classic inverted papilloma background (n = 2), or both (n = 1). Eleven cases with prostatic tissue revealed adenocarcinoma of the prostate [n = 6; Gleason score 6 (n = 3) or 7 (n = 3)], high-grade prostatic intraepithelial neoplasia (n = 1), benign prostatic hypertrophy (n = 3), or adenosis (n = 1). No patients had a prior history of either inverted papilloma or urothelial carcinoma, whereas 2 patients were diagnosed with high-grade urothelial carcinoma of the bladder synchronous with their inverted papilloma diagnosis. Only 1 of the 18 patients with available follow-up had a recurrence of inverted papilloma in the prostatic urethra. None of the other patients had local recurrences or recurrences at other locations in the urinary tract (mean follow-up 39.9 mo; range: 3 to 120 mo). Inverted papillomas of the prostatic urethra are benign lesions that are commonly detected incidentally and are not associated with a history of urothelial malignancy. Although urothelial carcinoma elsewhere in the genitourinary tract may occur simultaneously, malignant transformation or recurrence as a malignant lesion has not been identified in inverted papilloma of the prostatic urethra.