Villous adenoma of female urethra: An investigation of the mechanism of development regarding glandular neoplasms in the urinary tract

Villous adenomas are rare in the urinary tract. We herein report the fifth known such case while also making a review of the literature. A 54-year-old woman noticed a mass in her external genitalia and a tumor located on her external urethral orifice. The tumor was excised and pathologically confirmed to be a villous adenoma. Up to now, no sign of recurrence has been observed. However, we should be careful for malignant formation, because villous adenomas in the urinary tract frequently coexist with either adenocarcinoma or urothelial carcinoma.