Bullae are elevated, fluid-filled blisters ≥ 10 mm in diameter.
Epidermolysis bullosa acquisita can occur in all ages. The exact etiology of epidermolysis bullosa acquisita is not known, but data suggest it involves autoimmune antibodies directed against type VII collagen, a key component of the anchoring fibrils within the dermal-epithelial junction.
Multiple myeloma, amyloidosis, lymphoma, inflammatory bowel disease, and systemic lupus erythematosus have been associated with epidermolysis bullosa acquisita but the nature of the relationship is unclear.
Epidermolysis bullosa acquisita is distinct from the inherited disorder epidermolysis bullosa, which involves various genetic mutations.
Initial manifestations of epidermolysis bullosa acquisita are highly variable, sometimes resembling those of bullous pemphigoid. Bullous lesions are most often in areas subject to minor trauma, such as the extensor aspects of the elbows and the dorsal aspects of the hands and feet. Healing usually causes scars, milia (superficial epidermal inclusion cysts), and hyperpigmentation. Some patients have dystrophic nails and scarring alopecia, mucosal involvement, or ocular lesions leading to blindness.
Diagnosis of epidermolysis bullosa acquisita is confirmed by skin biopsy and direct immunofluorescence. Direct immunofluorescence shows linear deposits of IgG and complement at the basement membrane zone (dermal–epidermal junction).
Indirect immunofluorescence using salt-split skin may be needed for differentiation from bullous pemphigoid. In the salt-split technique, a sample of healthy skin from an unaffected person is incubated with sodium chloride to create an artificial blister. The sample is then incubated with serum from the patient and then fluorescent anti-IgG. The blister floor (dermal side) fluoresces in epidermolysis bullosa acquisita, whereas the blister roof (epidermal side) fluoresces in bullous pemphigoid.
The prognosis is variable, but disease course tends to be prolonged. High-quality evidence about treatments is lacking, and treatment recommendations are often anecdotal. However, in children, corticosteroids in combination with dapsone have shown benefit. In adults and in people with more severe disease, corticosteroids, dapsone, colchicine, cyclosporine, mycophenolate mofetil, IV immune globulin, rituximab, and azathioprine have been reported to be successful.
Important skin care measures include gentle cleansing of skin, vigilance in preventing skin trauma, and early detection and treatment of skin infections.