Background: The histological pattern of prostatic involvement by transitional cell carcinoma is still unclear. The present study was carried out in bladder carcinoma with prostatic involvement to clarify the histological invasion pattern and its association with primary lesions.
Methods: In the past 10 years, 83 cases of total cystectomy including prostatectomy underwent pathological diagnosis in our department. This study included 81 cases of transitional cell carcinoma (TCC), of which 11 showed prostatic involvement of bladder carcinoma. In these cases, the histological patterns of invasion were classified in relation to prostatic urethra, prostatic duct, stroma, lymphatic duct, capsule, vein and perineural invasion. Seventy cases without prostatic involvement were controls. The location, pathological grade, stage and lymphatic involvement of primary bladder carcinoma were compared in terms of prostatic involvement cases with control cases.
Results: Among those 11 cases, there were 3 cases in which only the prostatic duct was involved, 2 cases with invasion to only lymphatic duct, and involvement of both in 6 cases. One case of the prostatic duct involvement showed non-continuous invasion in the prostatic duct without prostatic urethra invasion, suggesting the possibility that non-continuous invasion could occur as a type of multicentric growth of TCC.
Conclusions: Suspected routes of invasion of bladder carcinoma into the prostate were; 1 continuous transductal, 2 trans-lymphatic ductal, 3a combination of the two. It appears necessary to consider the possibility of TCC occurring in the prostate simultaneously with bladder carcinoma as a part of multicentric growth. There was a tendency of prostatic involvement cases include the bladder neck and trigone, and show lymphatic duct involvement more than non-prostatic involvement cases.