Epidermolysis bullosa acquisita !
A rare autoimmune disease in which antibodies attack collagen anchoring the skin, causing fragile skin and blisters that heal with scars and milia.
Updated 2026-11-01
Structures involved
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Why it happens
- Collagen
- Basement membrane
- Extracellular matrix: collagen types, elastin, ground substance
- Where blisters form: pemphigus vs pemphigoid
What it is
A chronic acquired autoimmune subepidermal blistering disease caused by autoantibodies against type VII collagen, the main component of the anchoring fibrils that attach the epidermis to the dermis. It presents either as trauma-induced skin fragility or as an inflammatory eruption resembling other pemphigoid diseases.
Who gets it
Very rare (fewer than one case per million people per year in European data). It affects adults of any age, and occasionally children. No data exist for Colombia; it should be considered when a 'pemphigoid' does not behave as expected.
Causes
- Autoantibodies (mainly IgG) against the NC1 domain of type VII collagen
- Associated diseases: Crohn disease (most typical), and also rheumatoid arthritis, systemic lupus erythematosus, diabetes, amyloidosis, myeloma and lymphoma
- Genetic susceptibility linked to certain HLA class II alleles
Risk factors
- Inflammatory bowel disease, particularly Crohn disease
- Other autoimmune diseases
- Adulthood
- Mechanical friction or trauma (for the classic form)
Pathophysiology
Autoantibodies bind type VII collagen in the anchoring fibrils just below the lamina densa. Complement activation and neutrophil recruitment (inflammatory form), or loss of anchoring function (mechanobullous form), separate the epidermis from the dermis below the basement membrane. Because the split is deep, blisters heal with scarring and milia, similar to inherited dystrophic epidermolysis bullosa.
Classification
- Classic (mechanobullous, non-inflammatory): fragile skin and blisters on trauma-prone areas
- Inflammatory: bullous pemphigoid-like, mucous membrane pemphigoid-like, linear IgA-like and Brunsting-Perry forms
Symptoms and signs
- Tense blisters and erosions on non-inflamed skin over the backs of hands, knuckles, elbows, knees and feet
- Healing with atrophic scars, milia and colour change
- Nail loss and scarring hair loss in some patients
- Widespread itchy inflamed blisters in the inflammatory form
- Mouth, eye, oesophagus or larynx involvement in some cases
Diagnosis
- Clinical
- Suspect it in an adult with skin fragility and scarring blisters on trauma sites, or with a pemphigoid-like disease that leaves scars and milia.
- Tests
- Perilesional biopsy: subepidermal blister on routine histology; direct immunofluorescence shows linear IgG (often with C3) along the basement membrane, with a u-serrated pattern. Salt-split skin: antibodies bind the dermal side (floor), unlike bullous pemphigoid (roof). ELISA for anti-type VII collagen antibodies confirms the target. Check for porphyria and inflammatory bowel disease when suspected.
- Imaging
- Not needed for diagnosis; endoscopy if oesophageal symptoms.
Differential diagnosis
- Bullous pemphigoid (roof binding on salt-split skin)
- Mucous membrane pemphigoid
- Porphyria cutanea tarda and pseudoporphyria (also fragile, scarring skin on the backs of hands)
- Linear IgA bullous dermatosis
- Bullous systemic lupus erythematosus (also targets type VII collagen)
- Inherited dystrophic epidermolysis bullosa (from birth)
Goal of treatment
Stop new blisters, heal erosions, prevent scarring of skin and mucosae, protect eyes and airway and limit side effects of long-term immunosuppression.
Treatment
- Conservative
- Avoid friction and trauma, pad pressure points, use soft clothing, gentle wound care with non-adherent dressings, and drain large blisters while keeping the roof.
- Medical
- Systemic corticosteroids combined with steroid-sparing agents such as colchicine, dapsone, mycophenolate, azathioprine or ciclosporin; the disease is often difficult to treat.
- Medical
- Refractory disease: rituximab, intravenous immunoglobulin, immunoadsorption or plasmapheresis.
- Follow-up
- Regular eye, mouth and swallowing checks with ophthalmology and ENT; nursing monitoring for infection and drug toxicity.
Complications
- Scarring, milia and contractures of the hands
- Conjunctival scarring and vision loss
- Oesophageal and laryngeal strictures
- Secondary skin infection
- Adverse effects of long-term immunosuppression
Prognosis
Chronic, with flares and remissions over years. Response to treatment is often slower than in bullous pemphigoid. Some patients achieve remission, while mucosal disease determines long-term disability.
Test yourself
Think of the answer, then tap the question to see it.
What is the target antigen in epidermolysis bullosa acquisita?
Type VII collagen (anchoring fibrils).
How does salt-split skin help distinguish EBA from bullous pemphigoid?
In EBA antibodies bind the dermal floor; in bullous pemphigoid they bind the epidermal roof.
Which bowel disease is classically associated with EBA?
Crohn disease.
What do healed lesions of the classic form leave behind?
Atrophic scars and milia over trauma-prone sites such as the backs of the hands.
Related conditions
- Bullous pemphigoid
- Mucous membrane (cicatricial) pemphigoid
- Pemphigus vulgaris
- Porphyria cutanea tarda
- Dermatitis herpetiformis
- Crohn disease
- Systemic lupus erythematosus
Educational information, not medical advice. For any symptom, see a health professional.
Sources: Epidermolysis bullosa acquisita (DermNet, 2026).
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