Nephrogenic adenoma in a urethral diverticulum.

Nephrogenic adenoma (NA) is a rare benign metaplastic lesion of the urothelial tract that arises as a response to injury and chronic inflammation. Although the most common site for NA is the bladder, it can occur in any part of urinary tract lined by urothelium. NA can mimic minor variants of urothelial cancer, clear cell adenocarcinoma, and prostate adenocarcinoma, making a combination of histologic examination and immunohistochemistry essential for diagnosis. We hereby report a rare case of nephrogenic adenoma arising in a urethral diverticulum.