Epidermolysis Bullosa Acquisita at a Glance
- Rare, autoimmune subepidermal bullous disease due to immunoglobulin (Ig) G autoantibodies to type VII collagen.
- Etiology is unknown.
- Skin fragility, subepidermal blisters, residual scarring, and milia formation. Common sites are trauma-prone areas such as hands, feet, elbows, knees, sacrum, nails, and mouth.
- Related features may include an underlying systemic disease such as inflammatory bowel disease. May have erosions of the mucosa and esophageal stenosis.
- Pathology shows subepidermal bulla, fibrosis, milia formation, and positive direct immunofluorescence for IgG deposits at the dermal–epidermal junction.
- Treatment options are limited and often difficult.
Epidermolysis bullosa acquisita (EBA) is a sporadic autoimmune bullous disease of unknown etiology and with no gender, ethnic, or geographic predisposition. Although EBA does not have a Mendelian pattern type of inheritance, there may be some genetic predisposition to EBA and autoimmunity in African-Americans who live in the southeastern part of the United States.1 African-American patients in the southeastern part of the United States who have either EBA or bullous systemic lupus erythematosus (SLE) have a high incidence of the HLA-DR2 phenotype. The calculated relative risk for EBA in HLA-DR2+ individuals is 13.1 in these patients. These results also suggest that EBA and bullous SLE are immunogenetically related and that either the HLA-DR2 gene is involved with autoimmunity to anchoring fibril collagen or is some sort of a marker for some other gene that exists in linkage disequilibrium with it.1
EBA is a chronic, subepidermal blistering disease associated with autoimmunity to the collagen (type VII collagen) within anchoring fibril structures that are located at the dermal–epidermal junction (DEJ). Although the precise etiology of EBA is unknown, most of the evidence suggests an autoimmune etiology. The immunoglobulin (Ig) G autoantibodies to type VII collagen are associated with a paucity of normal-anchoring fibrils at the basement membrane zone (BMZ) separating the epidermis from the dermis and poor epidermal–dermal adherence. Although it is an acquired disease that usually begins in adulthood, it was placed in the category epidermolysis bullosa (EB) approximately 100 years ago because physicians were struck by how similar the clinical lesions of EBA were to those seen in children with hereditary dystrophic forms of EB. Direct immunofluorescence (DIF) of perilesional skin biopsies from EBA patients reveals IgG deposits at the DEJ.2 EBA antibodies bind to type VII collagen within anchoring fibrils (see Chapter 53).3,4
Anchoring fibrils anchor the epidermis and its underlying BMZ to the papillary dermis. Patients with hereditary forms of dystrophic EB (see Chapter 62) and EBA have decreased numbers of anchoring fibrils in their DEJ. This paucity of anchoring fibrils is associated with two similar clinical phenotypes, EBA and dystrophic forms of hereditary EB, because both diseases are characterized by skin fragility, subepidermal blisters, milia formation, and scarring. Although both EBA and hereditary forms of dystrophic EB are etiologically unrelated in terms of their underlying pathogenesis, they ...