Nephrogenic adenoma.

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.