Prostatic intraepithelial neoplasia characterized by the presence of morphologically malignant cells lining the acini and ducts. The malignant cells are enlarged, contain prominent nucleoli, and have increased nuclear/cytoloplasmic ratio. The malignant cells may grow within the ducts and acini in four architectural patterns: flat, tufting, micropapillary, and cribriform. The presence of high grade prostatic intraepithelial neoplasia in needle biopsy is a risk factor for the subsequent detection of carcinoma on repeat biopsy.