Comparative Study of Direct Immunofluorescence in Discoid Lupus Erythematosus and Bullous Pemphigoid.

Immunoreactants are found in the epidermal basement membrane in both lupus erythematosus and bullous pemphigoid (BP). To our knowledge, there are no comparative studies on direct immunofluorescence (DIF) of discoid lupus erythematosus (DLE) and BP. The authors studied DIF of lesional skins in 9 patients (2 males and 7 females) with DLE and 29 patients (11 males and 18 females) with BP to disclose the difference between these 2 diseases. IgG deposition was significantly more frequent at the epidermal basement membrane zone (BMZ) in the BP group than in the DLE group; however, IgA and IgM depositions were significantly more frequent at both the epidermal and follicular BMZs in the DLE group than in the BP group. In addition, the mean number of positive immunoreactants at both the epidermal and follicular BMZs was significantly larger in the DLE group than in the BP group. On an average, ≥3 immunoreactants were seen at the epidermal and follicular BMZs in DLE, whereas ≤2.5 immunoreactants were seen in BP. DIF may contribute to the differentiation between these 2 diseases.