Loss of high-molecular-weight cytokeratin antigenicity in prostate tissue obtained by transurethral resections

Staining of prostatic basal cells for the expression of high-molecular-weight cytokeratin has been suggested as a way of distinguishing benign from malignant prostate glands. We evaluated the utility of high-molecular-weight cytokeratin in the diagnosis of malignancy in prostate specimens obtained in various ways. Prostate tissues obtained from needle biopsies, transurethral resections, and total prostatectomies were immunostained with monoclonal antibody 34betaE12, an antibody directed against high-molecular-weight cytokeratins. Antiserum to high-molecular-weight cytokeratin only stained the basal cells in normal glands in 3 (12%) of 25 specimens obtained by transurethral resection. Other antigens, such as the alternate 10-nm filament protein vimentin, were unaffected and were detected in 100% of these specimens. However, keratin antigenicity in transurethral biopsies could be restored in these specimens by antigen retrieval in a low pH citrate buffer using a microwave heat technique. Keratin staining in needle biopsies and total prostatectomies was unaffected. In summary, our results indicate the technique of transurethral resection results in a specific loss of keratin antigenicity. This limits the utility of anticytokeratin 34betaE12 in interpreting transurethral resections without the application of antigen retrieval.