Monolayer of benign cuboidal to low-columnar cells and often with poke out cell nuclei (hobnail cells, image B).
Tubules have characteristic thickened peritubular basement membrane may resemble blood vessels or, if minute, signet ring cells.
The lumen may contain basophilic or eosinophilic secretions.
Immunohistochemistry: PAX-2+ and S100-A1+.
Papillary urothelial neoplasia: multilayered, with atypia, and is p63+.
Prostatic carcinoma: NA tubules in prostatic urethra may resemble and similarly express AMACR!; NA is PSA- or PSAP-.