Microscopic description and IHC:

The urothelium shows papillary projections lined by bland cuboidal cells with small nuclei and inconspicuous nucleoli. The stroma has an acute and chronic inflammatory infiltrate with abundant plasma cells. Mitotic figures are not readily identifiable. The cells are positive for PAX2, P504s (AMACR), and CK7.

Discussion:

Nephrogenic adenoma (metaplasia) is a benign proliferation of the urothelium associated with inflammation, repeated instrumentation, radiation, surgery, stones, BCG therapy, and renal transplantation. The patient’s history of multiple urinary issues and repeat procedures likely contributed to her development of this lesion. Nephrogenic adenomas can show a tubular, papillary, cystic or diffuse pattern lined by cuboidal epithelial cells without significant atypia. Occasionally smooth muscle involvement is present. These cells are positive for CK7, AMACR, and PAX2. A papilloma would not be AMACR positive and the benign appearance of the cuboidal lining cells makes the malignant answer choices less likely.

References:

Zhou, M., & Magi-Galluzzi, C. (2007). Chapter 1: Non-neoplastic diseases of the prostate. Genitourinary pathology. Philadelphia, PA: Churchill Livingstone/Elsevier.

Rosai, J., Ackerman, L. V., (2004). Chapter 17: Urinary Tract: Kidney, renal pelvis, and ureter-Bladder and male urethra. Rosai and Ackerman's surgical pathology. St. Louis, MO: Mosby.

CASE IMAGES