UCa involving the prostate that originates from prostatic urethra, periurethral glands and proximal prostatic ducts (image A) & (image B).
Strictly speaking, primary prostatic UCa are those arising within proximal prostatic duct urothelium, however, urethral and duct involvement often goes hand in hand and its difficult, if not impossible, to identify if the invasive UCa arose only from the ducts.
But must be distinguished from secondary bladder UCa that invades into the prostate. (pT4 bladder cancer, which has poorer prognosis)
Rare, 1-4% of prostate cancers in adults; secondary involvement by bladder UCa is more common (12% to 58%).
Carcinoma may spread within duct or acini without invasion of prostatic stroma and remains carcinoma in situ (not all UCa within prostate are invasive!).
Disease specific survival higher in UCa in situ of prostatic urethral glands, ducts, and acini versus UCa with prostatic stromal invasion.
Poorly differentiated prostatic adenocarcinoma: in contrast is PSA+ or PSAP+ and HMWK-, p63- and GATA3- (+ in UCa).