Epidermolysis bullosa acquisita (EBA) is a rare autoimmune disease characterized by blistering in layers of the skin in response to injury. This occurs mostly in the mucous membranes — tissue that lines body cavities such as the mouth, nose, and eyes — as well as in the hands, feet, knees, elbows, and buttocks. It usually emerges in adulthood, mostly when people are in their 40s or 50s.
Causes of EBA
EBA is caused by autoantibodies generated against a protein called type VII collagen. This is a major structural protein of anchoring fibrils, which are key in the attachment of the epidermis (the top layer of the skin) with the dermal layer underneath. The attack of the immune system on type VII collagen leads to the loss of anchoring between those two layers and results in the formation of blisters in response to minor injury. The event(s) that triggers the autoimmune response is unknown.
EBA has been reported in several family members, indicating there may be a genetic contribution to the condition.
Types, symptoms of EBA
EBA can be broadly classified into non-inflammatory and inflammatory types.
Non-inflammatory EBA, which typically overlays the classical/non-mechano-bullous form, is characterized by skin fragility, tense vesicles, and blisters on
the skin surface of hands, knees, knuckles, elbows, and ankles. The mucous membrane’s blisters rupture easily and lesions heal with significant scarring and milia (small white spots).
Mild cases of non-inflammatory EBA resemble symptoms of porphyria cutanea tarda, a rare disorder that affects the skin. Severe cases resemble hereditary recessive dystrophic epidermolysis bullosa.
Patients with inflammatory EBA show widespread eruptions involving the trunk, central body, extremities, and skin folds. In inflammatory EBA, blisters appear in both trauma-prone and non-trauma-prone areas.
Clinically, inflammatory EBA mimics other blistering conditions, such as bullous pemphigoid (BP), linear IgA disease, mucous membrane pemphigoid, or Brunsting-Perry (BP) pemphigoid. Patients may have symptoms of one or more different subtypes of inflammatory EBA.
BP-like inflammatory EBA
People with BP-like inflammatory EBA have widespread tense vesicles and blisters. This subtype affects the trunk region and skin folds, and is accompanied by generalized redness, itching, and plaque formation. It heals with minimal scarring and milia.
This subtype is characterized by linear deposits of IgA (a type of antibody) in the basement membrane zone — a layer between the epidermis and the dermis — and mucosal scarring.
This subtype is confined to the head and neck like Brunsting-Perry type mucous membrane pemphigoid. It usually heals with atrophic scars (depressions in the skin).
Mucous membrane EBA
This form affects mucous membranes of the mouth, eye, nose, esophagus, anus, and the genitals. It can result in significant mucosal scarring and dysfunction.
The primary aim of EBA treatment is to protect the skin by preventing blisters, promoting healing, and avoiding complications.
EBA can be treated with immunosuppressive agents, such as azathioprine or cyclophosphamide. Other possible medications include oral corticosteroids such as prednisone, or anti-inflammatory agents including dapsone or colchicine. Into-the-vein injection of immunoglobulins (antibodies), an approach used in other autoimmune conditions, also may be a choice for patients with this type of EB.
When patients do not respond to other therapies, they may be treated with rituximab, which is used to treat people with inflammatory conditions and forms of leukemia and lymphoma.
Last updated: July 20, 2021
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