p63/AMACR antibody cocktail restaining of prostate needle biopsy tissues after transfer to charged slides: a viable approach in the diagnosis of small atypical foci that are lost on block sectioning.

We assessed the utility of using a p63/a-methylacyl-coenzyme-A racemase (AMACR) antibody cocktail on destained H&E-stained sections. We transferred 61 stored (7-11 months old) and 10 recent (<1 month old) H&E-stained sections of prostate needle biopsy tissues to charged slides and subsequently stained them with a p63/AMACR immunohistochemical antibody cocktail. The AMACR and p63 staining intensities were compared with those obtained with the same antibody cocktail performed on sections recut directly from the paraffin block. Transfer of sections and subsequent immunohistochemical staining was successful in 69 (97%) of 71 cases. For stored cases, there were similar AMACR and p63 staining intensities in destained and recut sections in 55 (90%) and 11 (18%) of 61 cases, respectively. In recent sections, AMACR and p63 staining intensities were almost identical by both methods. We conclude that p63/AMACR cocktail immunostaining of destained H&E-stained sections is a viable approach in the workup of small "suspicious" foci in recently sectioned prostate needle biopsy tissues. This approach is best used when 2 or more H&E-stained sections harbor the suspicious focus, as we always recommended preservation of at least 1 H&E-stained section.