IgA epidermolysis bullosa acquisita may be more common than previously thought

Immunoglobulin A epidermolysis bullosa acquisita may be more common than previous data would indicate and is likely a separate entity from linear IgA bullous dermatosis, according to an investigation.

Mareike Becker, MD, of the department of dermatology, allergy, and venereology and the Lübeck Institute of Experimental Dermatology at the University of Lübeck in Lübeck, Germany, and colleagues described immunoglobulin A (IgA) epidermolysis bullosa acquisita (EBA) as “an autoimmune skin blistering disease with IgA autoantibodies directed against type VII collagen.”

They suggested that there is disagreement about whether this condition should be on the clinical spectrum of linear IgA bullous dermatosis (LABD) or categorized as a separate entity altogether.

The retrospective cohort study and case series included data for 300 patients diagnosed with IgA EBA, IgG EBA or LABD between October 2010 and July 2019. The aim was to define the clinical features and treatment responses of these conditions and to compare their prevalence rates. Demographic data were analyzed, as were immunopathologic and serologic data.

In addition, the analysis also included a series of four patients with IgA EBA. The researchers aimed to define clinical features and treatment responses in this group.

Results showed that there were 21 cases of IgA EBA in the cohort, comprised of 57% female subjects and 43% male subjects. There were 222 cases of LABD, broken down as 51% female subjects and 49% male subjects. For the 57 cases of IgG EBA, the breakdown was 51% female subjects and 49% male subjects.

Patients in the IgA EBA group had a median age of 64 years (range, 4 to 81 years), while those in the IgG EBA group had a median age of 56 years (range, 3 to 92 years). By comparison with IgG EBA, patients with LAPD had a median age of 70 years (range, 1 to 94 years; P = .002).

Clinical presentation for all patients with IgA EBA was heterogeneous and showed significant differences from the presentation in patients with anti-BP180 LABD.

The researchers observed a serration pattern in five patients with IgA EBA, 21 patients with LABD and eight patients with IgG EBA. The autoantibody deposition was n-serrated in all patients with LABD, while those with IgA and IgG EBA demonstrated a u-serrated autoantibody deposition. The researchers noted that this finding was consistent with previous data sets.

Looking at the IgA EBA case series, first-line therapy for all four patients was dapsone. However, only one patient responded to this drug. High-dose dexamethasone, rituximab and/or intravenous immunoglobulins were required to achieve partial clinical remission in the three patients who failed to respond to dapsone.

“The findings of this cohort study and small case series suggest that IgA EBA may be more common than expected and may require more intensive systemic treatment than LABD, suggesting it should be considered a separate disease entity,” the researchers wrote.