Background: Transrectal ultrasonography guided needle biopsy of prostate frequently used for early detection of cancer has faced the pathologists with a major diagnostic challenge. In recent years P504S has been used as a tumor cell marker for definitive diagnosis of prostatic cancer in small biopsy specimens.
Methods: 70 prostate needle biopsies and 6 transurethral resections (TURP) containing atypical foci as well as 40 morphologically unequivocal prostate cancer biopsies, including 8 with foamy features, were stained with P504S.
Results: 36 specimen out of 40 biopsies with unequivocal cancer, showed variable P504S staining (sensitivity, 90%) 2 minute cancer and 2 foamy cancer lacked P504S staining. of 76 cases with atypical foci (70 biopsies, 6 TURP), 18 were diagnosed as high-grade prostatic intraepithelial neoplasia (HGPIN) - 16 of them showing diffuse moderate P504S staining - and 58 had foci of atypical small acinar proliferation. 14 of the latter cases were highly suggestive of cancer, 4 of which lacked P504S staining. In 44 cases with benign atypical foci, 2 out of 14 cases with atypical adenomatous hyperplasia (AAH) and 1 of 2 post-radiation atypias showed focal weak P504S staining with remaining 28 cases being negative.
Conclusions: P504S has slightly lower sensitivity for detection of prostate cancer than that found previously. Heterogeneous expression patterns may explain negativity in some biopsy specimens with minute cancer. In atypical small acinar proliferations, diffuse positive P504S staining in atypical glands strongly supports cancer diagnosis, but negative staining does not exclude it. P504S seems to have low sensitivity for detecting minute and foamy prostate cancers. Most HGPINs show diffuse moderate P504S staining. AAH and benign glands may show focal P504S staining. We recommend using P504S along with morphologic examination and conventional basal cell markers.
