Epidermolysis bullosa acquisita (EBA): a rare acquired blistering skin disease

The NHS describes epidermolysis bullosa (EB) as a group of rare inherited skin disorders that make the skin very fragile. EBA is different. The NHS calls it an acquired form of EB with similar symptoms: like EB it causes the skin to blister easily, and it can also affect the mouth, throat and digestive tract, but it is not inherited and symptoms do not usually appear until later life.

The Primary Care Dermatology Society (PCDS) explains that EBA is a rare immunobullous condition in which patients may have chronic acquired, trauma-induced, subepidermal blistering, or a clinical picture similar to bullous pemphigoid. In several affected patients, autoantibodies are directed to type VII collagen, the major structural component of the anchoring fibrils that attach the basement membrane to the underlying dermis.

The PCDS notes an association with inflammatory bowel disease and with lymphoproliferative disorders, and that drug-induced EBA has been described. The NHS says it is not known exactly what causes EBA.

The PCDS describes two main presentations. The first, and most common, affects trauma-prone extensor skin surfaces. Tense blisters, which may be filled with clear or bloodstained fluid, appear mainly on areas of trauma such as the backs of the hands, elbows, knees, ankles and feet. The lesions heal with significant scarring, milia and changes in pigmentation, and the picture resembles the inherited form called dystrophic epidermolysis bullosa.

The second presentation is a generalised inflammatory form. Some of these presentations are indistinguishable from bullous pemphigoid and the lesions heal with less scarring. In both forms mucosal involvement is variable, but can be severe, and some inflammatory cases evolve into the more typical mechanobullous picture. The PCDS adds that people in whom mucosal symptoms predominate are now regarded as having mucous membrane pemphigoid.

Patient.info describes EBA as a chronic autoimmune subepidermal blistering disease of the skin and mucous membranes, causing blisters, scars and milia, mainly in the areas of skin prone to trauma.

The PCDS says patients are often referred to secondary care to obtain a diagnosis and for management. Two skin biopsies are required. An intact blister is taken for histology, and a second biopsy of the skin next to the blister is needed for direct immunofluorescence, which looks for antibodies bound in the skin. The PCDS says the sample must be examined the same day or placed in a suitable transport medium to preserve it, which is why the arrangement is made by the specialist team.

On direct immunofluorescence, IgG is deposited in a line along the dermo-epidermal junction. Salt-split skin studies can help to distinguish EBA from bullous pemphigoid, because in EBA the antibody is found on the floor of the blister. Blood tests are also used: the PCDS says circulating IgG autoantibodies targeting the skin basement membrane are present in approximately half of patients.

Because several blistering conditions look alike, the diagnosis rests on this combination of skin examination and laboratory tests rather than on appearance alone.

The PCDS says the primary aim of treatment is to protect the skin and reduce or stop blister formation, promote healing and prevent secondary infection, scarring and deformities. It also says that, given the rarity of the condition, there is little data to support an evidence-based strategy for the inflammatory component of EBA.

It lists many treatments that have been tried, including corticosteroids, dapsone, azathioprine, ciclosporin, colchicine, mycophenolate mofetil, intravenous immunoglobulin and the biologic rituximab, and says the mechanobullous variant often proves very resistant to treatment. These are specialist treatments, chosen and monitored by a dermatology team. Patient.info likewise says that there is no specific therapy for EBA.

The NHS explains the practical side of caring for fragile skin in EB generally: popping blisters with a sterile needle, applying protective dressings and avoiding things that make the condition worse, with medicines to treat infection or reduce pain. These approaches are described for inherited EB, so the dermatology team will advise which apply to acquired disease.

The PCDS says the prognosis is variable. People with a bullous pemphigoid-like picture may go into remission, but those with mechanobullous disease tend to be chronic. For many people, the focus is long-term skin protection and monitoring for complications such as infection and scarring.

DEBRA is described by both the NHS and the PCDS as the UK patient support organisation for people affected by inherited EB or by EBA. The PCDS says membership benefits include access to a community support team, financial support and benefits advice, information, respite breaks and opportunities to connect with others. The NHS also mentions a clinical team may pass information about people with EB to the National Congenital Anomaly and Rare Disease Registration Service, which people can opt out of.