Urothelial carcinoma and prostatic adenocarcinoma presenting as collision tumors

Urothelial carcinoma (UC) and prostatic adenocarcinoma (PAC) commonly occur in elderly patients and share common carcinogenic factors that could be identified in the urine. The presence of one tumor is known to be associated with an increased incidence of the other. Simultaneous occurrence of PAC and UC in the prostate is not uncommon; however, urinary bladder location of both lesions has not yet been reported. Furthermore, invasion into the urinary bladder wall by a PAC can also pose a diagnostic challenge with UC and other primary urinary bladder tumors. We report three patients presenting with UC and PAC within the urinary bladder. The patients were 80, 84 and 85 years old. All patients were diagnosed with high grade PAC and either had simultaneous at the initial diagnosis or developed UC during the follow up for PAC. Histopathological analysis pictured collision tumors consisting of an invasive component represented by high grade PAC and a superficial component composed of low or high grade UC. Both components displayed distinctive immunophenotypes: PAC was P63- /HMWCK- /PSA+ and UC was p63+/HMWCK+/ PSA-. In conclusion, awareness of this association is important in making the correct diagnosis, especially when dealing with urinary bladder biopsy material.