Circulating bullous pemphigoid autoantibodies in the setting of negative direct immunofluorescence findings for bullous pemphigoid: A single-center retrospective review

Background: Bullous pemphigoid (BP) autoantibody levels are generally elevated in patients with BP but can be present nonspecifically in patients without BP. Objective: To analyze the clinical findings of patients with elevated BP180 or BP230 autoantibody levels and negative direct immunofluorescence (DIF) study findings. Methods: We retrospectively reviewed records of patients seen at our institution during January 1, 2005-December 31, 2015, who were positive for BP180 or BP230 autoantibodies and had a negative DIF study finding. These patients' demographic characteristics and BP180 and BP230 levels were compared with those of a BP control group who were positive for BP180 or BP230 autoantibodies and had positive DIF study findings. Results: We identified 208 patients with BP autoantibodies but without positive DIF study findings. These patients' mean age and enzyme-linked immunosorbent assay values were significantly lower than those of the control group. Dermatitis was the most common final clinical diagnosis. Of the 208 patients, 41 (19.7%) had at least 2 years' follow-up. Four patients had positive DIF results upon repeating the test and ultimately received pemphigoid diagnoses. Limitations: Retrospective design with limited follow-up. Conclusion: Patients might harbor serum BP autoantibodies in the context of a wide range of dermatoses. Low positive BP180 and BP230 autoantibody levels should not be overinterpreted as evidence for BP in the setting of a negative DIF.