A 55-year-old male (non-smoker) presents with flank pain and is noted to have an 8 mm calculus in the right ureter with hydronephrosis. After laser lithotripsy, he undergoes cysto-uretoscopy that reveals a minute filiform lesion in the prostatic urethra, and minute fragments of black calculi in the right ureter.   

H&E photomicrographs and a synaptophysin immunostain are provided. 

What is your diagnosis?

A. Urothelial dysplasia due to calculus 

B. Benign urothelial papilloma

C. Papillary urothelial carcinoma, low grade

D. Prostatic ductal adenocarcinoma

E. Nephrogenic adenoma