[Formalin-resistant leukocyte differentiation antigens in dermatohistopathology]

The diagnosis of cutaneous leucocytic and particularly lymphocytic infiltrates with a considerable degree of reliability, has become possible owing to the use of monoclonal antibodies against leucocyte differentiation antigens. This method of diagnosis depends heavily on the availability of frozen biopsies, however, since most antigens are destroyed by the routine tissue processing, including formol fixation, paraffin embedding and alcohol dehydration. In recent years an increasing number of antibodies has become available that allow the detection of formalin-resistant leucocyte differentiation antigens and thus can be used on conventional paraffin sections. When using such antibodies, which will be invaluable in routine diagnosis and, furthermore, will allow the investigation of old biopsies, the dermatopathologist must be familiar with the exact distribution of the detected antigen and should be aware of crossreactivities with other structures. This review presents the most important antibodies and gives hints on their rational and economical use.