Usefulness of Cytokeratin 5/6 and AMACR Applied as Double Sequential Immunostains for Diagnostic Assessment of Problematic Prostate Specimens

Trpkov, Kiril MD, FRCPC
Bartczak-McKay, Joanna BSc, MLT
Yilmaz, Asli MD, FRCPC

Department of Pathology and Laboratory Medicine, Calgary Laboratory Services and University of Calgary, Calgary, Canada

Address reprint requests to Dr Trpkov: Anatomical Pathology, Rockyview General Hospital, Department of Pathology and Laboratory Medicine, Calgary Laboratory Services and University of Calgary, 7007 - 14 Street SW, Calgary, Alberta, Canada, T2V 1P9.

American Journal of Clinical Pathology 132(2):p 211-220, August 01, 2009. | DOI: 10.1309/AJCPGFJP83IXZEUR

We evaluated the usefulness of double immunohistochemical staining for cytokeratin (CK)5/6 and α-methylacyl coenzyme A racemase (AMACR) applied sequentially on 1 slide by assessing 223 foci in 110 consecutive prostate specimens. Double-chromogen reaction was used to visualize the antibodies: brown for CK5/6 and red for AMACR. Staining was scored as diffuse, focal, or negative. To establish the diagnosis, CK5/6 and AMACR were correlated with the morphologic features. All cancers lacked CK5/6 staining (100% specificity). AMACR showed diffuse or focal positivity in cancer, high-grade prostatic intraepithelial neoplasia, and atypia in 96.8% (120/124), 85% (22/26), and 80% (16/20) of cases, respectively. In atypical cases, diagnosis was because of non–immunohistochemical staining reasons in 80% of cases. In adenosis (n = 14), AMACR was diffusely positive in 4 cases (29%). Double immunohistochemical staining for CK5/6 and AMACR is a simple assay to perform and may be used as an alternative to antibody cocktails for routine evaluation of problematic prostate specimens.