CUTANEOUS LUPUS ERYTHEMATOSUS: COMPARISON OF DIRECT IMMUNOFLUORESCENCE FINDINGS WITH HISTOPATHOLOGY

Abstract Background. Direct immunofluorescence (DIF) is considered to be a major advance in the diagnosis of connective tissue diseases, particularly lupus erythematosus (LE); however, the reliability of the technique depends on several factors, such as age and site of the lesion, type of immunofluorescence, type of immunoglobulin, etc. False positives and false negatives can occur. Objective and Methods. To determine the diagnostic value of DIF we studied 18 clinically established cases of cutaneous lupus erythematosus (CLE). Lesional biopsies were subjected to routine histopathologic examination and direct immunofluorescence. The results were compared. Results. Direct immunofluorescence was positive in 72.7% and histopathology in 66% cases. Combination of the two techniques (with one or both methods giving characteristic findings) was positive in 83% cases. The most common antibody was IgG, seen in 77.8% cases. A homogeneous pattern of immunofluorescence, with IgG, was seen in 55.5% of the cases. Although histopathology gave positive or suggestive results in all cases, DIF was negative in two cases of early cutaneous LE. Conclusion. Although DIF is an extremely useful diagnostic tool, it should always be used in conjunction with histopathology and the combination of the two methods yields the best results.