Direct immunofluorescence in bullous pemphigoid: effects of extent and location of lesions.

We have reevaluated the previously reported conclusion that direct immunofluorescence in bullous pemphigoid is often negative in biopsy specimens from the legs. Duplicate tests from the trunk and legs were generally of equal intensity in a prospectively evaluated series of eight patients with generalized bullous pemphigoid. Also, in 36 patients evaluated retrospectively, the intensity of the direct immunofluorescence reaction correlated roughly with extent of disease, rather than with specific anatomic region. Localized disease predictably required less vigorous treatment to achieve control, but the intensity of the immunofluorescence reaction was not similarly predictive. Direct immunofluorescence is a less useful diagnostic test in localized bullous pemphigoid than in generalized bullous pemphigoid.