Molecular evidence for progression of nephrogenic metaplasia of the urinary bladder to clear cell adenocarcinoma.

Nephrogenic metaplasia or nephrogenic adenoma of the urinary tract may present a diagnostic challenge in surgical pathology practice. Previous case reports suggest the possibility of nephrogenic metaplasia progressing to clear cell adenocarcinoma, but a malignant potential of nephrogenic metaplasia is generally not acknowledged. A case of a 70-year-old female patient with multiple recurrences of nephrogenic metaplasia of the urinary bladder and subsequent development of clear cell adenocarcinoma is described. Immunohistochemical studies help to differentiate the 2 entities. Results of molecular studies, particularly comparative genomic hybridization analysis, suggest clonal evolution of nephrogenic metaplasia to clear cell adenocarcinoma in this case.