FLOOR-PATTERN SALT-SPLIT SKIN CANNOT DISTINGUISH BULLOUS PEMPHIGOID FROM EPIDERMOLYSIS-BULLOSA ACQUISITA - USE OF TOAD SKIN

Background and Design.-Patients with epidermolysis bullosa acquisita ( EBA) and bullous pemphigoid (BP) can present with similar clinical fea tures. These antigens have different phylogenetic origins. It was thou ght that sodium chloride split-skin immunofluorescence could reliably distinguish between BP and EBA. However, it has now been recognized th at both diseases can present with a floor pattern fluorescence on salt -split skin. A simple method is required to distinguish these diseases . Results.-Serum specimens from two patients presenting with pruritic blisters showing a floor pattern immunofluorescence on salt-split skin were found to have positive fluorescence on toad skin that has the BP and not the EBA antigen. The diagnosis of BP in these patients was co nfirmed by a prompt response to treatment with systemic steroids. Elec tron microscopy showed a split at the lamina lucida. Conclusions.-Bull ous pemphigoid can present with a floor pattern immunofluorescence on salt-split skin. The use of the skin from invertebrates like the toad may help in distinguishing BP from EBA.