Nephrogenic Adenoma of the Urinary Bladder: A Review of the Literature

Figure 1

(a) Comments: nephrogenic adenoma is a benign proliferative glandular lesion usually found in the urinary bladder. Bladder calculi, instrumentation, radiation therapy, repeated urinary tract infections, and trauma are the usual predisposing factors. A small percentage of cases arise following renal transplantation. Nephrogenic adenoma displays papillary, polypoid, tubular, or flat configuration and is lined by cuboidal or low columnar epithelium. (b) Comments: nephrogenic adenoma was an incidental finding in this bladder biopsy from a 77-year-old female with a history of urothelial carcinoma of the renal pelvis. The lesion shows tubulopapillary structures lined by cuboidal epithelium with chronic inflammatory cells in the stroma. Nine months later, she was found to have a suspicious “red velvety” area on follow-up cystoscopy. Biopsy showed recurrent nephrogenic adenoma. (c) Comments: nephrogenic adenoma is composed largely of papillary structures arising in the urinary bladder of a patient with history of calculi. A few small tubules are present at the base of the lesion. (d) Comments: high power view of previous image showing nephrogenic adenoma. The nuclei show an orderly arrangement along the surface. The stroma contains chronic inflammatory cells. (e) Comments: nephrogenic adenoma is composed of numerous small as well as cystically dilated tubules. The tubules are lined by plump vesicular nuclei with punctate nucleoli. Some of the tubules have hobnail appearance. Mitotic activity is not increased. (f) Comments: high power view of the previous image showing hobnail nuclei in some of the tubules of nephrogenic adenoma. The nuclei are hyperchromatic but the chromatin is smudged. Punctate nucleoli can be seen. The stroma contains abundant neutrophils, lymphocytes, and plasma cells. The following features are usually not found in nephrogenic adenomas: increased mitotic activity, significant cytologic atypia, solid areas, and deeply infiltrative pattern. (g) Comments: a small percentage of nephrogenic adenomas arise in renal transplant recipients. They most likely develop from renal tubular epithelial cells shed from the transplanted kidney. The immunoreactivity of nephrogenic adenomas for PAX2 and PAX8 markers (shown here) seems to support this hypothesis. PAX2 and PAX8 are transcription factors in the paired box (PAX) gene family. Both are expressed in normal renal tubular epithelium and in lesions derived from them. (h) Comments: cystoscopic view of nephrogenic adenoma in the bladder neck region of a 20-year-old male who presented with history of pelvic pain. The lesion consists of papillary and polypoid edematous-appearing structures. These figures have been reprinted from http://webpathology.com/ with permission from http://webpathology.com/: this permission is exclusive to this request specifically for this paper. Additional usage of any printed or electronic material for which http://webpathology.com/ holds would require copyright permission from http://webpathology.com/.

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