Objective: To evaluate the morphologic spectrum and clinical significance of ductal adenocarcinoma of the prostate (DAP).
Study design: We reviewed diagnostic criteria, including the value of immunohistochemistry, and outlined the prognostic implications of a diagnosis of DAP.
Results: DAP is composed of tall columnar cells displaying nuclear pseudostratification and several architectural patterns, including cribriform, papillary, solid and invasive glandular. Typically, there is marked cytologic atypia and a high mitotic count, although in some cases cytologic atypia can be minimal, causing diagnostic difficulties, particularly in needle biopsies. DAP is found in both the periurethral region and peripheral zone of the prostate and is considered high grade in the modified Gleason grading system. Immunostaining for prostatic-specific antigen and prostate-specific acid phosphatase is present in these tumors, a high percentage of which overexpress alpha-methylacyl-coenzyme A racemase. A basal cell layer can be seen in some of these tumors, which is probably due to tumor growth into preexisting ducts. This usually represents an advanced stage of tumor progression and is not a precursor of invasive carcinoma.
Conclusion: DAP are neoplasms of prostatic origin, and the terms endometrioid or endometrial adenocarcinoma are best avoided. The term ductal carcinoma is also inappropriate because this includes some urothelial carcinomas of ductal origin. DAP are aggressive tumors with a shortened average time to progression compared with acinar adenocarcinoma.