Atypical foci suspicious but not diagnostic of malignancy in prostate needle biopsies (also referred to as "atypical small acinar proliferation suspicious for but not diagnostic of malignancy").

OBJECTIVE: To review atypical focus suspicious but not diagnostic of malignancy in needle biopsies of the prostate, also referred to as "atypical small acinar proliferation suspicious for but not diagnostic of malignancy."

METHODS: A number of descriptive and somewhat confusing terms have been used to refer to a prostate tissue biopsy with small focus of atypical glands. Based on MEDLINE database searches, all aspects, including the synonymous terms, of atypical focus suspicious but not diagnostic of malignancy were examined.

RESULTS: An average of 5% of needle biopsy pathology reports show a diagnosis of atypical focus suspicious for malignancy. It may be composed of acini of small size, that is, smaller than normal ducts and acini, but may also include glands with a diameter similar to that of normal ducts and acini. It encompasses a variety of lesions, including benign mimickers of cancer and small foci of carcinoma that, for a variety of reasons, cannot be accurately diagnosed. Maximal diagnostic information should be gained on section stained with haematoxylin and eosin, with immunohistochemical stains used for confirmation. Its presence in a biopsy set is a strong predictor for concurrent or subsequent adenocarcinoma. The values range from 17% to 60%, the mean being 40.7%. The precise labelling of the initial biopsies is mandatory so that rebiopsy of patients with atypical foci can be directed in a more concentrated fashion into the region of the initial biopsy.

CONCLUSION: The presence of atypical focus suspicious but not diagnostic of malignancy in needle biopsies is an important predictor of cancer compared with biopsies from patients who lack this finding.