Pemphigus-like antibodies in bullous pemphigoid.

A patient had clinical, histopathologic, and direct immunofluorescent findings compatible with a diagnosis of bullous pemphigoid. In addition, the patient's serum contained pemphigus-like antibodies with different antigenic specificities than true pemphigus antibodies. Absorption of the patient's serum with AB substance failed to block the intercellular substance staining but allowed the demonstration of a basement membrane zone reactive antibody as well. Atypical cases such as this should not cast doubt on the usefulness of immunofluorescence in the diagnosis of bullous skin diseases.