Immunofluorescent and FISH analysis of skin biopsies.

Cutaneous biopsies are traditionally studied for the expression of cellular markers by immunoenzymatic techniques. However, immunofluorescent analysis is a valuable, and largely overlooked, ancillary technique that can resolve questions arising from conventional immunostaining, since it allows pairs of antigens to be simultaneously visualized. Furthermore, a novel technique, based on a combination of immunoperoxidase and immunofluorescent staining, allows three markers to be demonstrated together. Fluorescent microscopy also allows skin biopsies from lymphoma cases to be analyzed for chromosomal abnormalities by the fluorescent in situ hybridization (FISH) technique, which is now applicable to routine biopsy samples. In this review, we describe the technical aspects of immunofluorescent and FISH analysis of routine cutaneous biopsy samples.