Epidermolysis bullosa acquisita
What is epidermolysis bullosa acquisita?
Epidermolysis bullosa acquisita (EBA) most commonly presents as an acquired form of mechanobullous disorder. It is a very rare disease in which tense blisters appear at sites of trauma.
Epidermolysis bullosa (EB) is the name given to a group of inherited blistering diseases that are present from birth. Unlike EB, EBA is not inherited and usually presents in adult life.
EBA blisters tend to be localised to areas that are easily injured such as the hands, feet, knees, elbows, and buttocks. Sometimes there is mucosal involvement with blisters forming in the mouth, nose and eyes. EBA may mimic other inflammatory blistering diseases, most often bullous pemphigoid.
Who gets EBA and why?
EBA usually occurs in the fourth and fifth decade of life. Males and females of all races can be affected.
Current evidence points to EBA being an autoimmune blistering disease. Researchers have detected immunoglobulin G autoantibodies directed against the NC1 domain of type VII collagen in several affected patients. Type VII collagen is the major structural component of anchoring fibrils. These attach the basement membrane to the underlying dermis. The loss of anchoring fibrils leads to the formation of blisters just under the epidermis within an area known as the lamina densa.
Some patients with EBA have been reported to have other health problems most often Crohn disease, systemic lupus erythematosus, amyloidosis, multiple myeloma and rarely carcinoma of the lung and lymphoma. Other patients only have a skin problem. The reason why autoantibodies are produced is unknown.
What are the clinical features of EBA?
EBA has several distinct clinical presentations.
|Non-inflammatory or mildly inflammatory EBA affecting trauma-prone extensor skin surfaces||
|Generalised inflammatory EBA|
|Predominantly mucous membrane form of EBA||
How is EBA diagnosed?
The following tests should be performed to establish a diagnosis of EBA.
- Skin biopsy shows the presence of a blister under the epidermis (subepidermal bulla) and an infiltrate of mixed inflammatory cells in the dermis.
- Direct immunofluorescence of a skin biopsy shows an immune-mediated disease process. Autoantibody immunoglobulin G (IgG) is deposited in a line along the dermoepidermal junction.
- Indirect immunofluorescence of serum (a blood test) reveals the presence of circulating IgG autoantibodies that target the skin basement membrane and type VII collagen.
Other tests sometimes used to confirm the diagnosis include:
- Skin biopsy for direct and indirect immunoelectron microscopy
- Blood tests for immunoblotting, enzyme-linked immunosorbent assay (ELISA) and immunoprecipitation
What is the treatment for EBA?
The primary aim in the treatment of EBA is to protect the skin and stop blister formation, promote healing and prevent complications.
Because EBA is considered an autoimmune disease it is reasonable to use immunosuppressive agents to modify or reduce autoimmune responses and decrease the production of autoantibodies. These may include:
- Mycophenolate mofetil
- Intravenous immunoglobulin.
Due to the rarity of the disease, it is difficult to be sure which drug is the most effective.
Other important management strategies include:
- Treatment of any underlying disease.
- Consultation with other specialists such as dentist and ophthalmologist.
- Avoid direct physical trauma to skin surfaces.
- Avoid hard or brittle food or food with high acid content in patients with oral involvement.
What is the prognosis?
EBA is a chronic inflammatory disease that has periods of partial remissions and exacerbations. If treated and cared for properly, patients can expect to live a normal lifespan. Problems that may arise include:
- Infection of open wounds and sores
- Severe scarring which may cause deformities and restriction of movement
- Periodontal disease
- Conjunctival scarring and blindness
- Side effects of medication