Nephrogenic adenoma of the urinary bladder

The nephrogenic adenoma (NA) is a benign metaplastic lesion of the urothelium and is attributed to chronic irritation of the mucosa, by injury, infection, stone disease or intravesical instrumentations. We present our experience on this morbid entity, its clinical appearance in the urinary bladder, its frequency and relapses. Furthermore we reviewed the related recent literature and focused on its potential to neoplastic degeneration and the value of the new diagnostic modalities.

Four patients with NA of the urinary bladder are presented. The papilloid or polypoid formations observed by the cystoscopy were identified after the TUR, as NA of the urinary bladder. Their mean follow-up was 3.5 years.

Remission of the symptoms was observed after TUR in all patients. Three out of four patients presented 1-7 relapses, while in one case, after seven NA relapses, a urothelial carcinoma of the bladder was diagnosed.

Unlike histological features, the clinical - endoscopic characteristics of NA are non-specific. Even if it is not definitely considered like a premalignant condition, NA has to be followed up frequently and long lasting, because of its high recurrence rate. The combination of Cytology, Flow cytometry, DNA image analysis and Fluorescence in situ hybridization of bladder washings or voided urine, are of high value in monitoring NA of the urothelium.