Cutaneous Direct Immunofluorescence Testing Direct immunofluorescence (DIF) test can be performed on skin or mucosa obtained in the physician’s office. All biopsy specimens are examined for the presence of bound immunoglobulins (IgG, IgM, IgA), complement C3 and fibrinogen. IF testing is particularly useful for confirmation of the following: immunobullous diseases (pemphigus, IgA dermatitis, bullous pemphigoid, pemhigoid gestationis, epidermolysis bullosa acquisita, dermatitis herpetiformis), connective tissue diseases (lupus, dermatomyositis), and vasculitis. If tests may be diagnostic when dermatopathologic studies are only suggestive, nonspecific, or negative.
Selection of biopsy sites:
Immunobullous Diseases- Perilesional skin with the exception of skin to rule out/in dermatitis herpertiformis (DH). For DH- non-lesioned skin is preferred
Connective Tissue Diseases- Established lesional skin (best an active 6 month or older lesion)
Vasculitis – Lesional skin less than 24 Hours old.
Specimens for DIF should be places in Michel’s Solution. They should not be placed in formalin. All jars must have two (2) identifiers clearly written and match exactly with the specimen identifier and specimen labelling on accompanying req. The specimen can be transported at room temperature. For best results it should be received (and frozen) within 5 days of biopsy. Do not place on ice, dry ice, or freeze the Michel’s Solution
48 hours. Test processed Tuesday, Thursday & Saturday