Multiple and repeated sampling increases the sensitivity of direct immunofluorescence testing for the diagnosis of mucous membrane pemphigoid

Background Mucous membrane pemphigoid (MMP) is an autoimmune disease characterized by the predominant blistering of mucosal surfaces and the linear deposition of complement, IgG, or IgA along the basement membrane detected by direct immunofluorescence (DIF) test. Objective To assess the impact of multiple and repeated DIF sampling on establishing the diagnosis of MMP. Methods We reviewed the results of DIF studies in 136 nonlesional biopsies from 78 patients who were immunologically confirmed to have MMP. Results Thirty-six of 52 patients (69%) who underwent only 1 biopsy at the first workup were positive. In 13 cases, the initial single biopsy was negative, and later biopsies were positive. Twenty-two of 26 patients (85%) who underwent multiple biopsies at the initial workup showed ≥1 positive DIF test result. Simultaneously obtained biopsies yielded discordant positive and negative findings in 11 patients. Overall, 74 of 78 patients (95%) had ≥1 positive result by DIF test. In the remaining 4 cases, the diagnosis was confirmed by the detection of circulating autoantibodies against BP180. Limitations This is a retrospective, single-center study. Conclusion Our data demonstrate that multiple and repeated biopsies increase the sensitivity of the DIF test for MMP diagnosis. Negative DIF test findings in cases clinically suggestive of MMP should prompt repeat biopsies.