Significance of duct-acinar dysplasia in prostatic carcinogenesis.

Duct-acinar dysplasia of the prostate is defined as a premalignant lesion characterized by cytologic, and especially nuclear, abnormalities that resemble those of carcinoma and affect the lining epithelial cells of preexisting ducts and acini. A progressive continuum of cytologic abnormality is divided into three grades, with grade III identified by the presence of numerous large nucleoli. Foci of carcinoma have been identified at their point of origin from dysplastic ducts, which confirms the malignant potential of this lesion. Foci of dysplasia are found in roughly 80% of prostates with invasive carcinoma and 40% of glands without cancer. It is concluded that the majority of prostate cancers probably arise within dysplasia foci. Foci of grade III dysplasia occasionally evolve by proliferation of cells to fill duct lumens. The intraluminal cell masses display a cribriform pattern, which has previously been interpreted as a variant of invasive Gleason grade 3 carcinoma. Dysplasia is further linked biologically to malignant transformation by the immunohistochemical demonstration of progressive loss of cytoplasmic differentiation markers and inappropriate overexpression of some markers during the evolution of dysplasia.