Nephrogenic adenoma of the bladder: a single institution experience assessing clinical factors.

INTRODUCTION: Nephrogenic adenoma (NA) was first described by Davis in 1949 as a "hamartoma" of the bladder. There are many proposed predisposing factors for NA including chronic inflammation, renal transplantation, and bladder cancer. We examined our experience with NA to determine predisposing factors and determine if there was any increased risk for development of subsequent malignancy.

MATERIALS AND METHODS: All patients with a pathologic diagnosis of bladder NA from 2001-2013 were included. Patient history, clinical factors including possible predisposing factors for NA, and follow-up were reviewed.

RESULTS: Among 60 patients, 68% were males with an average age of 61, an average BMI of 28.7, and 60% had a smoking history. In evaluating pro-inflammatory factors, 26.7% underwent either Bacillus Calmette-Guerin or mitomycin C, 30% had recurrent urinary tract infections, and 25% had a history of catheterization. Recurrence of NA after initial resection occurred only in 14.7% of patients who underwent follow-up cystoscopy. A history of concurrent bladder cancer was seen in 41.7% of patients, but there were no cases of de novo bladder cancer diagnosed after NA.

CONCLUSION: To the best of our knowledge, this is the largest series of patients with NA of the bladder. NA occurs in a heterogeneous population of patients, but most often with underlying inflammation. NA occurred concurrent with bladder cancer; however there were no cases of de novo bladder cancer after NA, reassuring that NA is likely a benign reactive condition.