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P504S Immunostaining Boosts Diagnostic Resolution of “Suspicious” Foci in Prostatic Needle Biopsy Specimens

Zhong Jiang MD, Kenneth A. Iczkowski MD, Bruce A. Woda MD, Maria Tretiakova MD, PhD, Ximing J. Yang MD, PhD
DOI: http://dx.doi.org/10.1309/7T7RJCCL84JGXH3L 99-107 First published online: 1 January 2004

Abstract

From 1.5% to 9.0% of prostatic needle biopsy specimens disclose atypical small acinar proliferations (ASAPs) suggestive of malignancy, carrying an approximate 45% predictive value for cancer. We applied keratin 34βE12 and P504S monoclonal immunostains to 93 cases that were judged as ASAP after H&E staining alone. Forty-one ASAP foci survived recutting for both immunostains. Three urologic pathologists independently assigned post–keratin 34βE12 diagnoses of cancer, ASAP, high-grade prostatic intraepithelial neoplasia, or benign and then reviewed P504S slides and assigned final diagnoses. Eight foci (20%) were resolved unanimously after keratin 34βE12 staining; 18 (44%) were resolved by 1 or 2 evaluators and 29 (71%) by at least 1. According to whether post–keratin 34βE12 ASAP designation was given by 3, 2, or 1 evaluator(s), P504S immunostaining unanimously resolved an additional 5 (12%), 10 (24%), or 23 (56%) of 41 ASAP foci and cumulatively, 31 foci (76%). Among 35 men (excluding 6 with cancer in other cores of the original biopsy), these immunostains could have permitted cancer diagnosis in 11 (31%), without repeated biopsy. Thus, the consensus diagnosis rate improved from poor to good after supplementing 34βE12 immunostaining with P504S.

Key Words:
  • Prostate cancer
  • Atypical small acinar proliferation
  • P504S
  • AMACR
  • α-Methylacyl CoA racemase
  • Biopsy