Nephrogenic Adenoma

Synonyms

Nephrogenic metaplasia

Definition

Metaplastic change characterized by small tubules lined by a single layer of cuboidal, flat, or hobnail cells containing eosinophilic secretion with features similar to mesonephric tubules.

Clinical Features

• Incidence

  This is an uncommon lesion. Most patients have a previous bladder surgery or irritants such calculi or trauma, or kidney transplantation.

• Age

  Usually seen in adults but rare in children

• Sex

  Male: female: 3:1

• Site

  The bladder is the most common (55%) followed by urethra (41%) or ureter (4%).

• Treatment

  Resection

• Outcome

  Benign outcome

Macroscopy

These are less than 1 cm polypoid, flat, or papillary lesions. Large size examples have been reported.

Microscopy

The most common microscopic pattern is tubular (Fig. 1). The tubules are small, hollow, and round and sometime elongated. Other patterns are cystic (Fig. 2), papillary, and polypoid and less frequently with a diffuse pattern. Tubules and cysts are lined with cuboidal, hobnail...