www.kjurology.org DOI:10.4111/kju.2010.51.6.398 Urological Oncology Pathologic Results of Radical Prostatectomies in Patients with Simultaneous Atypical Small Acinar Proliferation and Prostate Cancer Kwang Ho Kim, Yun Beom Kim, Jeong Kee Lee, Yoon Jung Kim1, Tae Young Jung Departments of Urology and 1Pathology, Seoul Veterans Hospital, Seoul, Korea 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 sig- nificance 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 map- ping, we evaluated the RP specimens that were close sections to the ASAP on prostate needle biopsy. All tissues were examined by immunohistochemistry with high molec- ular weight cytokeratin (34βE12), 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 en- tity, in other words, prostatic adenocarcinoma. Aggressive approaches including more extended repeat biopsy with additional biopsy of the site of the ASAP are needed to diag- nose PCa in patients with ASAP. Key Words: Needle biopsy; Prostatectomy; Prostatic neoplasms; Surgical pathology This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Article History: received 4 May, 2010 accepted 27 May, 2010 Corresponding Author: Tae Young Jung Department of Urology, Seoul Veterans Hospital, 6-2, Dunchon 2-dong, Gangdong-gu, Seoul 134-791, Korea TEL: +82-2-2225-1739 FAX: +82-2-484-4604 E-mail: urodoct@hotmail.com INTRODUCTION The term ‘atypical small acinar proliferation (ASAP)’ was introduced by Bostwick et al to indicate suspicious glands with insufficient cytological or architectural atypia for the diagnosis of a definitive adenocarcinoma in prostate biop- sies [1]. The incidence of ASAP in prostate biopsies was 0.4% to 23.4% in 12 consecutive studies [2]. The clinical sig- nificance of ASAP is its predictive value for prostate cancer (PCa) in a repeat biopsy, which ranged from 34% to 60% in similar studies [3,4]. On this account, current recom- mendations for patients with ASAP in their initial biopsy are subsequent biopsy within 3 to 6 months irrespective of follow-up prostate-specific antigen (PSA) values [5]. 　Immunohistochemical stains with benign prostate basal cell markers such as high molecular weight cytokeratin (34βE12) or p63 and markers of cancer such as alpha-meth- ylacyl CoA racemase (AMACR/P504S) have been used for the differential diagnosis of ASAP and adenocarcinoma, al- though neither stain confirms a definitive diagnosis for Korean Journal of Urology Ⓒ The Korean Urological Association, 2010 398 Korean J Urol 2010;51:398-402