Carcinoma in situ of the bladder extending into the seminal vesicles.

Involvement of the urethra or distal ureter in 30 to 50 per cent of the patients with carcinoma in situ of the bladder is well known. Carcinoma in situ of the bladder extending to the seminal vesicles rarely has been mentioned. We discuss 2 patients with extension of carcinoma in situ into the seminal vesicles and replacement of the normally present cylindroid mucosal lining. Carcinoma in situ of the ureter, bladder and prostatic ducts also was present in both patients.