7,9) Another papillary/ polypoid lesion that might also enter into the broad differential is the papillary variant of
nephrogenic adenoma, mainly because it is frequently misdiagnosed or misinterpreted.
Nephrogenic adenoma of the urinary bladder is a rare lesion which could easily be confused with or could easily be misdiagnosed as a number of malignant lesions of the urinary bladder.
The differential diagnosis may be sometimes challenging and includes primarily the urothelial (transitional cell) carcinoma and rarely the
nephrogenic adenoma, the paraganglioma and the carcinoid tumours.
The histological differential diagnosis of paraganglioma includes nested variant of TCC, inverted papilloma and
nephrogenic adenoma.
Several lesions can have an exophytic papillary or polypoid cystoscopic appearance, including papillary urothelial neoplasms, polypoid cystitis, and
nephrogenic adenoma.
1]
Nephrogenic adenoma (also named nephrogenic metaplasia) is a benign entity and a common mimic of adenocarcinoma; this presents a diagnostic challenge in the interpretation of bladder biopsies.
The histologic differential diagnosis of miillerianosis of the urinary bladder encompasses several benign and neoplastic conditions, including cystitis glandularis, urachal remnants,
nephrogenic adenoma, primary adenocarcinomas of the urinary bladder, and secondary spread from a minimal-deviation adenocarcinoma of the uterine cervix.
Vesical
nephrogenic adenoma is a rare, benign entity that appears most commonly in middle-aged males.
The benign lesions include cystitis cystica, cystitis glandularis, von Brunn nests,
nephrogenic adenoma, mesonephric remnant, intestinal metaplasia, and urachal remnant.
Perhaps the most controversial aspect of
nephrogenic adenoma is its derivation and whether it represents a metaplasia or a benign tumor.
25,27)
Nephrogenic adenoma is the most important differential diagnosis.
This case is an example of a
nephrogenic adenoma with some unusual morphologic features; however, given the patient's history of previous resections, this is not an unexpected diagnosis.
