‘Suction split’ as a routine method to differentiate epidermolysis bullosa acquisita from bullous pemphigoid1

BACKGROUND AND DESIGN: Epidermolysis bullosa acquisita (EBA) and bullous pemphigoid (BP) are diseases with similar clinical, histological, and immunofluorescent findings. Diagnosis requires the use of immunoelectron microscopy, immunoprecipitation or immunoblotting, but in recent years the differential diagnosis has been based on a cheaper technique named salt split skin. This study demonstrates that with a suction blister the fracture is at the same level as that obtained with the sodium split method and that it is also faster and cheaper. Suction blisters on normal skin and autoimmune perilesional bullous lesions, obtained with a hand vacuum pump, were studied by direct immunofluorescence and electron microscopy to evaluate the level of the split on normal suction split skin. Normal human split skin was also used as a substrate for an indirect immunofluorescent study using sera of patients with BP (68 sera), EBA (10 sera) and cicatricial pemphigoid (CP) (16 sera). Direct immunofluorescent examination was also done on perilesional skin after artificial separation obtained with a hand-vacuum pump in patients with the same diseases listed above (32 BP, 11 CP, 6 EBA). RESULTS: On normal human skin split by suction or sodium chloride (NaCl; 1 mol/l) direct immunofluorescence and electron microscopy demonstrated that the split is at the lamina lucida level. Indirect immunofluorescent study of both normal human skin and perilesional skin split using suction as a substrate showed IgG deposits localized on the floor of the suction blister in all cases of EBA, whereas in over 88% of cases of BP and in over 62% of CP the IgG were localized on the roof. Similar results were obtained with direct immunofluorescence in perilesional skin. CONCLUSIONS: 'Suction split' represents a simple technique to differentiate EBA from BP. This method provides final response in a few hours compared to at least 1-2 days with the sodium split method. Furthermore, the suction split method is cheaper and the tissue can be re-utilized for molecular biology and immunohistochemical studies.