Nephrogenic adenoma

Abstract

Nephrogenic adenoma is an uncommon benign lesion. Its pathogenesis is as yet unclear although various theories have been proposed, including the embryological and inflammatory theory. The proposal that nephrogenic adenoma originates from the implantation of exfoliated renal tubular cells is lately gaining wider acceptance. Careful histological examination is essential to accurately identify this lesion and to differentiate it from other locally arising malignant lesions. The role of immunohistochemistry cannot be undermined in the diagnosis of nephrogenic adenoma, although histological diagnosis is usually conclusive. The possibility of nephrogenic adenoma should always be in the differential diagnosis when evaluating patients with predisposed urinary tract symptoms.

Flat pattern of nephrogenic adenoma: previously unrecognized pattern unveiled using PAX2 and PAX8 immunohistochemistry

“…2,3 However, recognition of this lesion is crucial since nephrogenic adenoma cannot only present as a urothelial neoplasm cystoscopically, but may also be misdiagnosed microscopically as invasive urothelial carcinoma with glandular differentiation or microcystic variant, signet ring cell carcinoma and clear cell carcinoma with hobnail cells as well as metastatic prostate carcinoma or renal cell carcinoma. Therefore, familiarity with the different growth patterns, cytologic features and characteristic stroma of nephrogenic adenoma is important.…”

“…However, we hypothesize that the frequent presence of this flat pattern may be an important factor related to the high recurrence rate of nephrogenic adenomas (30-80%). 2,3 As most nephrogenic adenomas are detected as a small (up to 1 cm) incidental lesion via cystoscopy, identification of the true extent of nephrogenic adenoma, which may assume a flat pattern growth at its periphery contiguous with the adjacent urothelium, is practically impossible. Thus, fragments of flat nephrogenic adenoma may remain in the bladder after transurethral resection and possibly give rise to recurrences.…”

“…Microscopically, nephrogenic adenomas are typically composed of tubules, cysts or papillae lined by flat to polygonal cells with a large nucleus and middle-sized nucleolus supported by loose fibrous stroma with different amounts of acute or chronic inflammation. 2,3 By immunohistochemistry, nephrogenic adenomas are positive for the renal tubule markers cytokeratin 7 (CK7), CD10, alpha-methylacyl-coenzyme A racemase (AMACR), PAX2 and PAX8, but negative for bladder urothelium or prostate antigens. [4][5][6][7][8] The transcription factors PAX2 and PAX8 (paired box genes) are crucial proteins during the embryonic and fetal development of several organs, particularly intermediate mesoderm and Mü llerian-derived tissues, and are expressed in nearly 100% of nephrogenic adenomas in some series.…”

Nephrogenic adenoma in elderly patients: Three case reports

“…Nephrogenic adenoma (NA) is an uncommon benign lesion of the urothelial mucosa of the urinary tract (1,2). In 1949, Davis reported the first identified case of NA as a 'hamartoma of the urinary bladder' (3).…”

“…The usual clinical presentation is hematuria, dysuria and frequency of micturition (10). Several predisposing factors have been reported to be associated with NA, in adults as well as in children, including genitourinary trauma, chronic inflammation, prior surgery, renal calculi, repeated instrumentation, irritated anatomical anomalies and pelvic irradiation, bacillus Calmette-Guérin (BCG) immunotherapy and diverticuli (1,8,9,11,12).…”