Direct Immunofluorescence (DIF)
How to send a specimen for DIF Testing
Skin or mucosal specimens for Direct Immunofluorescence testing must be sent in Michel's Transport Medium; a 4mm punch is recommended. This test cannot be performed on specimens fixed in formalin. CTA Pathology will provide bottles of Michel's Transport Medium to you.
The specimen can be transported at room temperature. Importantly, the specimen must be received (and frozen) within 5 days of biopsy.
Below are our guidelines for obtaining Direct Immunofluorescence biopsies for different diseases:
Pemphigus and Pemphigoid Groups (including linear IgA bullous dermatosis and chronic bullous disease of childhood)
Biopsy erythematous perilesional skin or mucosa. Avoid erosions, ulcers, and bullae while obtaining tissue adjacent to active lesions. Label as perilesional skin.
Biopsy normal-appearing skin, 0.5-1.0 cm away from lesion. Label as perilesional skin.
Lupus Erythematosus & Other Collagen Vascular Diseases
Involved areas of skin such as erythematous or active borders are preferred biopsy sites to confirm the diagnosis of lupus erythematosus, either discoid or systemic. Label as involved skin. Avoid ulcers, old lesions, and facial lesions, if possible. Uninvolved, nonexposed skin is the preferred site to detect a lupus band as may be found in systemic lupus erythematosus. Should unexposed skin be desired, buttock or medial thigh is suggested. Label as uninvolved, nonexposed skin.
Vasculitis versus Urticaria
The erythematous or active border of a new lesion is preferred. Avoid old lesions and ulcers. Label as involved skin. If appropriate skin lesion is not present, diagnosis may sometimes be made from uninvolved skin.
Porphyria Cutanea Tarda
Biopsy involved skin. Avoid old lesions and ulcers. Label as involved skin.