The progression of nephrogenic metaplasia of the urinary bladder to clear cell adenocarcinoma: a case report.

Nephrogenic metaplasia (or nephrogenic adenoma) and clear cell adenocarcinoma of the bladder are uncommon lesions that cause diagnostic dilemmas for pathologists due to their similar morphologic features. Nephrogenic metaplasia describes a lesion in the lower urinary tract that is composed of small tubules resembling renal medullary tubules. It has been suggested that nephrogenic metaplasia may progress to clear cell adenocarcinoma but this possibility is not widely accepted. We present a case of clear cell adenocarcinoma of the bladder arising from nephrogenic metaplasia and discuss the evidence behind the association of these two distinct rare lesions.