Diagnosing EBA is multi-step process

February 1, 2007

Because the condition is rare, there is no one standard medication that is administered.

National report - Clinicians can use agents off-label to treat epidermolysis bullosa acquisita (EBA), a condition that is rare in pediatrics and is diagnosed via a several-step process.

EBA typically occurs in adulthood and is a mechanobullous subepidermal autoimmune blistering disease that presents with tense vesicles and pus-filled blisters on extensor surfaces such as hands, knees, knuckles, elbows and ankles. About 10 percent of patients will present with mostly mucosal involvement, similar to that seen in patients with cicatricial pemphigoid.

A recent panel of experts suggested this group of EBA should be labeled mucus membrane pemphigoid. If the mucous membrane form of EBA is excluded, there are two clinical forms of the condition:

Unlike epidermolysis bullosa, EBA is a noninherited condition. In screening for the condition, clinicians should ensure patients do not have a family history for blistering disorders.

The diagnosis of the condition is a multi-step process: A skin biopsy will indicate a blister under the epidermis and an infiltrate of mixed inflammatory cells in the dermis; direct immunofluorescence of serum (a blood test used on salt-split skin) reveals the presence of circulating IgG autoantibodies that target the skin basement membrane; and, most commonly, the noncollagenous domain NC1 and NC2 of collagen VII of the anchoring fibrils.

In adulthood, the condition can present with other morbidities such as Crohn's, systemic lupus erythematosus, amyloidosis and multiple myeloma. Some of these comorbidities may be chronic in nature.

These comorbidities do not typically present alongside EBA when it occurs in childhood, according to Catherine McCuaig, M.D., a pediatric dermatologist and associate professor of dermatology and pediatrics at Sainte-Justine Hospital, University of Montreal, Montreal, Quebec, Canada.

"You need to do a work-up to assess if children have any comorbidities," Dr. McCuaig tells Dermatology Times.

Dr. McCuaig published a case study of EBA in the Archives of Dermatology in 1989 where she suggested that searching for associated immunologic abnormalities and HLA-DR typing can assist in the understanding of EBA. She also stresses that it's key to distinguish EBA from hereditary mechanobullous disease in children, for EBA can mimic hereditary dystrophic epidermolysis bullosa.

In that particular case, EBA was diagnosed by direct immunofluorescence of perilesional skin, indirect immunofluorescence on normal epithelium and saline-split skin, and direct immunoelectron microscopy, among other techniques.

"Response to therapy is variable," Dr. McCuaig notes.

Apart from corticosteroids, other agents that have been tried include those designed to reduce autoimmune responses and the production of autoantibodies.

Therapies that can provide significant clinical benefit include prednisone, azathioprine and other immunosuppressants such as mycophenolate mofetil. Others include intravenous immunoglobulin, dapsone, colchichine, anti-CD20 antibody rituximab and extracorporeal plasmaphotopheresis.

Because the condition is rare, no one standard medication is administered, Dr. McCuaig says.