Absence of serum prostate-specific antigen and loss of tissue immunoreactive prostatic markers in advanced prostatic adenocarcinoma after hormonal therapy: a report of two cases.

We report two cases of advanced prostatic adenocarcinoma (PA) showing complete loss of three tissue immunoreactive prostatic markers, ie, prostate-specific antigen (PSA), prostatic acid phosphatase (PAP), and Leu-7 (CD57), with absence of elevated serum PSA level, despite tumor progression after hormonal therapy with or without radiotherapy. The pretreatment serum PAP in the first case and serum PAP and PSA in the second case were elevated. In both cases, the prostatic adenocarcinoma in the initial transurethral resection specimens showed positive immunoreactivity with three prostatic markers. After treatment, in both cases, the serum PSA were undetectable, and tumor cell immunostaining for three prostatic markers was negative. In addition, the posttreatment tumors in both cases showed increased number of tumor cells with neuroendocrine differentiation in comparison those in the pretreatment tumors. Although early PA without elevated serum level of PSA is common, advanced PA with absence of elevated serum PSA, associated with presence of tissue immunoreactive prostatic markers are rare. This is the first report of advanced prostatic adenocarcinomas showing loss of tumor cell prostate-specific markers with absence of elevated serum PSA level after hormonal therapy despite tumor progression.