Atypical small acinar proliferation in the prostate: clinical significance in 2006.

About 2% of contemporary prostate needle biopsy specimens contain collections of small acini that are suspicious for cancer but that fall below the diagnostic threshold and are reported as atypical small acinar proliferation suspicious for but not diagnostic of malignancy. Prostate cancer has been identified in specimens from subsequent biopsies in up to 60% of cases of atypical small acinar proliferation, indicating that this finding is a significant predictor of cancer. Identification of atypical small acinar proliferation warrants repeat biopsy for concurrent or subsequent invasive carcinoma.