The controversial diagnostic term atypical small acinar proliferation (ASAP) has gained some acceptance as a legitimate way for pathologists to describe minute foci of small prostatic acini that raise the suspicion of carcinoma but that fail to attain the requisite diagnostic threshold for carcinoma.
To investigate the practice patterns of clinicians following this diagnosis and to identify clinicopathologic parameters that may be of influence.
All cases with a diagnosis of ASAP on a prostate biopsy specimen during a 7-year period were retrieved from our computerized database. Cases with concurrent diagnoses of adenocarcinoma and/or prostatic intraepithelial neoplasia were excluded. Medical and pathologic records for the remaining patients were reviewed and correlated with pathologic data.
Fifty-five (2.8%) of 1964 prostate biopsies performed during this period provided the diagnosis of ASAP, of which 36 met our study criteria. The average age of the patients was 65 years, and the mean total prostate-specific antigen (PSA) level was 6.41 ng/mL. The rate of biopsy subsequent to an ASAP diagnosis was 67% (24/36), and the mean duration to subsequent biopsy was 246 days (median, 182 days; range, 71-728 days). Adenocarcinoma was diagnosed in 9 (38%) of 24 specimens taken during the subsequent biopsy. Neither age nor PSA level significantly predicted a greater likelihood for subsequent biopsy. Additionally, among patients who received a subsequent biopsy, the aforementioned parameters were not predictive of carcinoma in the second biopsy. The average number of cores following an ASAP diagnosis (6 cores) did not differ significantly from the average at initial biopsy (7.18 cores, P =.64). Pathology report characteristics, such as inclusion of a descriptive note or explicit recommendation of a second biopsy, did not significantly increase the likelihood of a subsequent biopsy. Reasons for a delay in or lack of a subsequent biopsy following an ASAP diagnosis were miscellaneous and attributable to the patients in most cases.
The diagnosis of ASAP generates a subsequent biopsy in two thirds of cases after an average duration of 246 days. Although closer follow-up may be recommended based on the high rate of association with carcinoma on subsequent biopsy, we found no evidence that any delays in or lack of a subsequent biopsy is attributable to a lack of understanding on the part of urologists of the significance of the diagnosis.