MRI of prostatic urethral mucinous urothelial carcinoma: Expanding the differential diagnosis for T2 hyperintense prostatic masses.

We report the case of a 66-year-old previously healthy man presenting with blood and mucus in his urine. Cystoscopy revealed a mass in the prostatic urethra, and endoscopic biopsy showed adenocarcinoma in situ with mucinous features. Endorectal multiparametric prostate MRI demonstrated a 1.9 cm T2 hyperintense mass in the peripheral zone of the left prostatic apex with extension into the urethral lumen. No diffusion restriction or early enhancement was seen in the mass. Radical prostatectomy was performed, and final pathology demonstrated a mucin-producing urothelial adenocarcinoma arising from the prostatic urethra. The peripheral zone T2 hyperintense abnormality correlated with abundant pools of mucin extending into the prostatic stroma and surrounded by neoplastic prostatic glandular cells. We conclude prostatic urethral mucinous urothelial carcinoma should be included in the differential diagnosis for T2 hyperintense prostatic masses.