Derm Cases · Dermatology / Immunobullous disease
OSCE — trauma-induced scarring bullae in an adult: diagnose epidermolysis bullosa acquisita
An 8-minute OSCE station distinguishing EBA from bullous pemphigoid using milia/scarring, salt-split skin (floor vs roof), type VII collagen autoimmunity, IBD association, and stepwise management of treatment-resistant disease including mucosal red flags.
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Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station distinguishing EBA from bullous pemphigoid using milia/scarring, salt-split skin (floor vs roof), type VII collagen autoimmunity, IBD association, and stepwise management of treatment-resistant disease including mucosal red flags.
Brief (to candidate)
A 55-year-old man develops tense blisters after minor trauma on the elbows, knees and hands. Lesions heal with milia and atrophic scarring. He has long-standing Crohn's disease. Prior clinicians called it bullous pemphigoid, but response to steroids alone has been poor. You have 8 minutes to diagnose EBA, separate it from BP with immunofluorescence strategy, screen complications, and outline management.
[5]Candidate instructions
- Describe the mechanobullous clinical phenotype.
- Name the target antigen and key serologic/IF tests.
- Explain salt-split skin floor vs roof interpretation.
- Link inflammatory bowel disease and list differentials.
- Outline first-line and refractory treatment plus mucosal red flags.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Recognition | Adult-onset trauma-induced tense bullae on extensors/trauma sites; heals with milia and scarring; mechanobullous phenotype classic for EBA (inflammatory variants exist)[1][2] |
| Antigen | Autoantibodies (usually IgG) to type VII collagen (anchoring fibrils of DEJ)[1] |
| Salt-split IF | On salt-split skin, EBA immune deposits localise to the dermal floor; bullous pemphigoid to the epidermal roof — critical exam discriminator[2][3] |
| Work-up | Perilesional DIF, salt-split IIF or dermal ELISA/immunoblot for type VII collagen when available; H&E subepidermal blister; screen IBD (esp. Crohn), other autoimmune disease |
| Mucosal risk | Examine mouth/eyes/genital mucosa; ocular involvement → urgent ophthalmology (symblepharon, vision threat) |
| Management | Wound care, trauma avoidance; systemic therapy often needed — colchicine, dapsone (selected), corticosteroids ± immunosuppressants; refractory disease may need IVIG, rituximab, or other advanced therapy; recognise treatment resistance vs BP[2] |
| Safety | Reassess diagnosis if 'BP' is scarring/milia-rich and treatment-refractory; coordinate GI care for Crohn |
Model key actions
- Diagnose mechanobullous EBA with milia/scarring and trauma induction.[1]
- Confirm type VII collagen autoimmunity; salt-split floor staining vs BP roof.[2][3]
- Screen Crohn's/IBD and mucosa; plan multi-agent immunosuppression for resistant disease.
Common errors
- Calling all adult tense bullae bullous pemphigoid.
- Forgetting salt-split floor vs roof.
- Missing IBD association.
- Ignoring ocular/mucosal disease.
- Expecting easy steroid monotherapy response as in classic BP.
References5ShowHide
- [1]Kim JH, Kim SC. Epidermolysis bullosa acquisita. Journal of the European Academy of Dermatology and Venereology, 2013.PMID 23368767
- [2]Koga H, Prost-Squarcioni C, Iwata H, et al. Epidermolysis Bullosa Acquisita: The 2019 Update. Frontiers in medicine, 2018.PMID 30687710
- [3]Prost-Squarcioni C, Caux F, Schmidt E, et al. International Bullous Diseases Group: consensus on diagnostic criteria for epidermolysis bullosa acquisita. British Journal of Dermatology, 2018.PMID 29165796
- [4]Antonelli E, Bassotti G, Tramontana M, et al. Dermatological Manifestations in Inflammatory Bowel Diseases J Clin Med, 2021.PMID 33477990
- [5]Goyal N, Rao R, Shenoi SD, Pai S. Epidermolysis bullosa acquisita and anti-p200 pemphigoid as major subepidermal autoimmune bullous diseases diagnosed by floor binding on indirect immunofluorescence microscopy using human salt-split skin Indian J Dermatol Venereol Leprol, 2017.PMID 28749386