Pemphigus patients with initial negative levels of anti-desmoglein: A subtype with different profile?

Pemphigus is a blistering autoimmune disease that is characterized by autoantibodies against desmogleins (Dsg), including anti-Dsg1 and anti-Dsg3. Despite the diagnosis of diseases, the anti-Dsg test by enzyme-linked immunosorbent assay (ELISA) is negative in a small group of pemphigus patients. The aim of this study was to evaluate the clinical course, clinical symptoms, and response to treatment in pemphigus patients with negative levels of anti-Dsg1 and anti-Dsg3. In this study, the data of pemphigus patients referred to Razi Hospital were retrospectively collected from the medical records from 2016 to 2020. Eight patients, whose initial anti-Dsg1/anti-Dsg3 was negative by the ELISA test, were enrolled and their clinical course, clinical signs, and response to treatment were evaluated. The mean age of the subjects (8 females) was 38.75 ± 12.09. The most common phenotype of the subjects was pemphigus vulgaris (PV) with mucosal involvement. Additionally, the common site of blister inception was mouth of the patients. The mean prednisolone dose received by the patients at the initiation was 32.5 ± 13.62 mg/day. According to Pemphigus disease area index (PDAI), six patients had mild severity, while two cases had moderate severity. Among the patients, six subjects received rituximab (RTX). Also, five patients experienced remission after 6.2 ± 5.21 months. PV is the most common phenotype of the disease and mucosal involvement is more common in patients with negative anti-Dsg-1/3 results. The severity of the lesions in most of the patients is mild at baseline and most patients seems to respond to RTX therapy and reach remission.