Purpose: The incidence of adenocarcinoma on a subsequent biopsy following a diagnosis of atypical small acinar proliferation (ASAP) ranges from 34% to 60%. We reexamined radical prostatectomy (RP) specimens of patients diagnosed as having synchronous ASAP with prostate cancer (PCa) to evaluate pathological entities and the clinical significance of ASAP.
Materials and methods: From January 2007 to December 2008, a total of 118 patients who had been diagnosed with adenocarcinoma on prostate needle biopsy underwent RP. Forty-six of the 118 patients (39%) were diagnosed as having synchronous ASAP with PCa on the prostate needle biopsy. Using whole-mount sections and prostate mapping, we evaluated the RP specimens that were close sections to the ASAP on prostate needle biopsy. All tissues were examined by immunohistochemistry with high molecular weight cytokeratin (34betaE12), p63, and AMACR/P504S added to initial H&E stains by one pathologist.
Results: Thirty-six of the 46 patients (78%) were diagnosed as having adenocarcinoma at sites of ASAP on the initial prostate needle biopsies. The Gleason score was 5 to 6 in 22 patients (61%), 7 in 3 (8%), and unknown due to multifocal and microfocal lesions in 11 (31%). The tumor volume of 14 of the 36 patients (39%) was 0.5 cc or less and was unknown due to multifocal and microfocal lesions in 8 (22%).
Conclusions: Most ASAP on initial prostate needle biopsy was a true pathological entity, in other words, prostatic adenocarcinoma. Aggressive approaches including more extended repeat biopsy with additional biopsy of the site of the ASAP are needed to diagnose PCa in patients with ASAP.
Keywords: Needle biopsy; Prostatectomy; Prostatic neoplasms; Surgical pathology.