Direct immunofluorescence of skin using formalin-fixed paraffin-embedded sections.

The technique of direct immunofluorescence has been applied to skin biopsy specimens fixed in formalin and embedded in paraffin wax. The results have been compared with those obtained by using snap-frozen biopsy specimens from the same patients. Trypsinisation of the dewaxed material allowed subsequent detection of immunoglobulins, complement, and fibrinogen. When compared to the fluorescence in the snap-frozen specimens, the staining in the paraffin sections was less bright and there was a higher rate of negatives. Even so, it was possible to establish the diagnosis in most cases of pemphigus, pemphigoid, and lupus erythematosus.