Multilocular prostatic cystadenoma with high-grade prostatic intraepithelial neoplasia.

Multilocular prostatic cystadenoma is a rarely encountered neoplasm located in the midline between the bladder and rectum that is either attached to the prostate by a pedicle or separate from the prostate entirely. Histologically and immunohistochemically these lesions resemble benign prostate tissue. We report the first case of this entity for which multifocal high-grade prostatic intraepithelial neoplasia (PIN) is identified. Conceptually, the finding of high-grade PIN in multilocular prostatic cystadenomas provides further evidence that these lesions are fully analogous to the prostate gland not only in their morphology and immunohistochemistry but also in their predilection for the same diseases.