[Comparative immunofluorescence study of actinic keratosis and chronic discoid lupus erythematosus].

Regarding systemic (SLE) and chronic discoid lupus erythematosus (CDLE), the diagnostic value of the lupus band test ist generally accepted. In the literature, however, there are but few obligatory criteria concerning the definition of a positive lupus band. In order to illustrate the influence of sunlight on the evolution of junctional deposits of immunoglobulins, we examplarily studied actinic keratosis (AK) as a chronic light-dependent dermatosis. The junctional deposits in AK were qualitatively and quantitatively compared with the lupus band typical for CDLE. In CDLE we mostly found more distinct band-like junctional deposits of immunoglobulins and complements. Light-dependent, non-specific junctional patterns of immunofluorescence similar to LE, therefore, require clear morphological criteria of immunohistology.