Mucosal DIF biopsy shows high sensitivity for diagnosing MMP

Direct immunofluorescence microscopy bested serologic analysis as a diagnostic method for mucous membrane pemphigoid, according to a study.

“An accurate diagnosis of mucous membrane pemphigoid (MMP) is essential to reduce diagnostic and therapeutic delay,” Hanan Rashid, MD, of the department of dermatology, Center for Blistering Diseases, University Medical Center Groningen, the Netherlands, and colleagues wrote.

In the retrospective cohort study, they aimed to evaluate the diagnostic accuracy of direct immunofluorescence microscopy (DIF) on mucosal biopsy specimens and immunoserology in a cohort of 787 patients with suspected MMP.

Participants were accrued at a single tertiary care center between January 2002 and March 2019. In addition to microscopy data from a human salt-split skin substrate (SSS), eligibility criteria dictated that each participant also have an optional DIF test on a skin biopsy sample and at least one immunoserologic test available for analysis.

The primary outcome measure was the diagnostic accuracy not only of DIF, but of indirect immunofluorescence microscopy (IIF) SSS and immunoblot for BP180 and BP230, according to the findings.

Results showed that 15.4% of participants in the cohort were diagnosed with MMP. Of these 121 patients, 41.3% were men and 58.7% were women. The mean age was 60.1 years.

Monosite involvement was observed in 55.4% of individuals with MMP. The oral site was most common, with 42.1% of patients affected in this area.

The sensitivity of DIF on a perilesional buccal biopsy was 89.3% compared with a 76.7% sensitivity rate of DIF on a normal buccal biopsy, which the researchers noted was a nonsignificant difference.

A positive DIF only in the oral mucosa was observed in three patients who demonstrated solitary ocular involvement.

A skin biopsy confirmed the MMP diagnosis in six patients with a negative mucosal DIF, according to the findings.

IIF SSS was associated with 44.6% sensitivity and 98.9% specificity. By comparison, immunoblot had a higher sensitivity at 66.1% but a lower specificity at 91.3%.

The researchers concluded that mucosal DIF biopsy is the most sensitive method for diagnosing MMP. They added that this method is superior to serologic analysis.

“A biopsy can be taken from either perilesional or normal buccal mucosa,” they wrote. “An additional DIF biopsy of another mucosal site or of affected or unaffected skin may increase the diagnostic yield and is recommended in patients with negative DIF results and high clinical suspicion.”