The Value of Direct Immunofluorescence on Proteinase-Digested Formalin-Fixed Paraffin-Embedded Skin Biopsies.

Direct immunofluorescence (DIF) on frozen tissue (DIF-F) is the method of choice for the identification of immune deposits present in skin and other tissues. DIF can also be performed on formalin-fixed paraffin-embedded tissue (DIF-P) after antigen retrieval with proteases and has proven to be of value in renal pathology. However, its utility in skin biopsies has not been fully examined.