Differences in direct immunofluorescence staining patterns in epidermolysis bullosa acquisita and bullous pemphigoid.

BACKGROUND: Both bullous pemphigoid (BP) and epidermolysis bullosa acquisita (EBA) are characterized by linear IgG deposits along the basement membrane zone (BMZ). Although these diseases can be distinguished by special tests, the staining pattern on direct immunofluorescence (DIF) is identical.

OBJECTIVE: The purpose of the present study was to reevaluate DIF as a diagnostic tool in differentiating EBA from BP.

METHODS: We performed DIF studies on biopsy specimens from eight consecutive patients with EBA and 18 consecutive patients with BP.

RESULTS: In five of eight cases of EBA, C3 deposition was essentially absent. IgG was the predominant class of immunoglobulins in the deposits and was present along the BMZ in all eight cases. C3 was present in 17 of 18 cases of BP. IgG was the predominant immunoglobulin present in 15 of these 18.

CONCLUSION: Patients with EBA are more likely to have linear IgG staining along the BMZ without concomitant C3 deposition than are patients with BP. This difference may be a function of the ability of the autoantibodies to fix complement.