Intraductal Carcinoma of the Prostate

Intraductal carcinoma of the prostate (IDC-P) is characterized by\udmalignant cells expanding the lumen of prostatic ducts and acini\ud(Figure 1) (1). The basal cells are completely or partially preserved\ud(Figure 2). The malignant cells filling the gland cause trabecular,\udcribriform, micropapillary or solid pattern (2,3,4,5). The glands\udwith intraductal carcinoma are more than twice the diameter of\udnormal peripheral zone glands and may show branching typically\udat the right angles (Figure 3). The contour of the glands is smooth\udin contrast to benign and high-grade prostatic intraepithelial\udneoplasia (H-PIN). There may be comedonecrosis (2). The cells\udshow generally two different populations. The outer layer cells\udare pleomorphic with marked nuclear atypia and six times larger\udthan benign nuclei. They are mitotically active and stain poorly\udfor prostate specific antigen (PSA) immunohistochemically (1).\udThe inner group cells are small (Figure 3). They are monomorphic\udcuboidal cells with abundant cytoplasm and strong PSA staining.\udThere may be extracellular mucin (Table 1).\udThe differential diagnosis of IDC-P includes cribriform H-PIN,\udinvasive cribriform adenocarcinoma, ductal adenocarcinoma, and\udintraductal spread of urothelial carcinoma. H-PIN lacks solid and\udcribriform patterns, comedonecrosis, two different cell populations, and marked nuclear enlargement. Ductal adenocarcinoma has\udpapillary structures with fibrovascular cores, and basal cells are\udusually absent. Cribriform adenocarcinoma shows irregular and\udinvasive borders and absence of basal cells. Urothelial carcinom