Prostatic intraepithelial neoplasia: a lesion that may be confused with cancer on prostatic ultrasound.

Most prostatic adenocarcinomas reveal a hypoechoic peripheral zone lesion on transrectal ultrasonography. Numerous benign processes can have similar transrectal ultrasound findings. We report 8 cases of transrectal ultrasound-guided prostatic biopsies of peripheral zone hypoechoic lesions that demonstrated prostatic intraepithelial neoplasia, a presumed premalignant lesion. Immunohistochemistry using an antibody directed against cytokeratins 5 and 14 was performed to exclude carcinoma. Of the men 2 had invasive carcinoma on repeat biopsy and 1 had carcinoma diagnosed on subsequent transurethral resection. Patients with prostatic intraepithelial neoplasia on biopsy of hypoechoic peripheral zone lesions merit careful monitoring.