A novel tissue preservation medium for immunoperoxidase staining of skin biopsies.

The requirement for unfixed tissue is a major drawback in the use of immunohistochemistry for the diagnosis of inflammatory and neoplastic disease. We describe the use of a novel gel transport medium (U.K. Patent No. WO 90/07703, international patent applications pending) to preserve unfixed skin biopsies from allergic contact dermatitis reactions for 1 week prior to frozen section and immunohistochemistry for leucocyte antigens. The medium can be used with biopsies up to 6 mm3 and does not require any alteration in the usual frozen section or immunohistochemical staining procedures. The results show a subjective improvement in both morphology and staining quality. We believe this to be due to improved cutting of the sections and reduced background staining of collagen. This transport medium should be of considerable benefit to the provision of a clinical service, because it allows tissue for immunohistochemical examination to be taken at locations distant from the pathology laboratory.