Abstract: 【Abstract】 Objective To investigate the morpaology of prostate intraepithelial neoplasia(PIN) and its significance. Methods 103 specimen of prostate biopsy, including 26 cases with prostate carcinoma and 77 cases of benign prostate hyperplasia (BPH), were collected. Morphological features were reviewed. The expression of 34BE12, P63 and p504s were assayed in all patients by immunohistochemistry. Results High grade intraepithelial neoplasia(HGPIN) was found in 23 of 26 case with prostate carcinoma. There was no low grade intraepithelial neoplasia (LGPIN) to be observed in the patients above. Of 77 cases with BPH, intraepithelial neoplasia were found in 24 cases,(including 18 cases of LGPIN and 6 cases of HGPIN ). The histological types of HGPIN were mainly cluster and micropapilla structures (accounting for 92%). Immunohistochemistry: Among 29 cases with HGPIN , the discontinuous expression of 34βE12 was observed in basal cell around gland. In those of prostate carcinoma with HGPIN, P504s expression was from poor to moderate positive in the lesions of HGPIN near carcinoma(+-++), whereas was from moderate to strong expression in those away from carcinoma(++-+++); In the patients who were BPH with HGPIN, the positive expression was only observed in the two of 6 cases. The positive ratio of P504s was 82% in the case with HGPIN. Conclusion HGPIN is only precancerous lesion of prostate carcinoma. It must be differentiated from atypical hyperplasia of small alveolar gland and intraductocarcinoma of prostate; P504s is specific to HGPIN and carcinoma of prostate. The expression of it is probably associated with the progression of these tumors.; The correct diagnosis of HGPIN must depend on morphologic features and immunohistochemistry stain.

Key words: prostate, carcinoma, intraepithelial neoplasia, immunohistochemistry stain