Right panel: hematoxylin- and eosin-stained section of a prostate biopsy showing atypical adenomatous hyperplasia, with its characteristic small crowded glands mimicking prostatic adenocarcinoma. However, minimal cytologic atypia and patchy basal cells (arrowheads) are present. Left panel: Immunohistochemical staining with 34bE12 demonstrates basal cells (arrowheads) in an area of atypical adenomatous hyperplasia.
