Tissue protection immunohistochemistry: a useful adjunct in the interpretation of prostate biopsy specimens and other selected cases in which immunostains are needed on minute lesions.

Performing immunohistochemical analysis on minute lesions is a challenging task, primarily because they frequently disappear when the paraffin block is recutfor immunostaining purposes. This is a particularly common occurrence with prostate biopsy specimens, in which immunostains for high-molecular-weight cytokeratin commonly are used as an adjunct to H&E examination for aiding in the interpretation of minute "suspicious" lesions. We describe an original method designated tissue protection immunohistochemistry, that allows the performance of high-molecular-weight cytokeratin immunostains (or other immunostains) on previously stained H&E slides. The method described does not require destaining of H&E-stained sections, and it allows the preservation of the H&E stain on adjacent levels that may be present on the same slide. The method described requires that the original H&E-stained sections be placed on adhesive slides, but it has the advantages of eliminating the requirement of a paraffin block for immunostaining and eliminating the need for saving intervening unstained sections for possible immunohistochemical analysis.