Derm Cases · Dermatology / Autoimmune blistering disease
OSCE — flaccid bullae and oral erosions: pemphigus vulgaris work-up and first-line therapy
An 8-minute OSCE station on recognition of pemphigus vulgaris, distinction from bullous pemphigoid, biopsy/IF strategy, severity concepts, and modern first-line rituximab-based management with steroid stewardship.
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NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on recognition of pemphigus vulgaris, distinction from bullous pemphigoid, biopsy/IF strategy, severity concepts, and modern first-line rituximab-based management with steroid stewardship.
Brief (to candidate)
A 42-year-old woman has painful oral erosions for 8 weeks followed by flaccid blisters and erosions on the trunk and scalp. Nikolsky sign is positive. She is losing weight because she cannot eat. You have 8 minutes to diagnose, plan investigations, and outline first-line management.
Candidate instructions
- Recognise pemphigus vulgaris morphology and mucosal-first presentation.
- Differentiate from bullous pemphigoid, pemphigus foliaceus, and Stevens–Johnson syndrome.
- Plan histology + direct immunofluorescence correctly (sites).
- Outline first-line therapy including rituximab pathway and steroid use.
- Assess severity / complications (infection, fluid loss, nutrition) and safety-net.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Recognition | Painful oral erosions often first; flaccid bullae that rupture easily; erosions; Nikolsky sign positive; middle-aged adult[1][2] |
| Differential | BP: elderly, tense bullae, pruritus, mucosa usually spared, Nikolsky −; PF: seborrhoeic/crusted, mucosa spared; SJS/TEN: acute drug-triggered necrolysis, severe mucosal multi-site disease |
| Investigations | Lesional biopsy for H&E (suprabasal acantholysis, tombstoning) + perilesional DIF (intercellular IgG/C3 net-like); ELISA anti-Dsg3 ± Dsg1; consider PNP/PAMS if severe stomatitis + neoplasm red flags[2][3] |
| Severity & support | Mentions PDAI concept; assess oral intake, secondary infection, fluid/electrolyte loss; wound care and analgesia |
| First-line Rx | Rituximab (anti-CD20) is preferred first-line disease-modifying therapy with systemic corticosteroids per modern guidelines; steroid-sparing (MMF/AZA) when rituximab unavailable; infection prophylaxis/monitoring as indicated[4][5] |
| Safety | Never delay diagnosis with endless oral steroids alone; screen infection risk; stop unnecessary drugs; urgent derm/hospital if extensive erosions or inability to swallow |
| Communication | Explains chronic autoimmune disease, long-term follow-up, and that oral disease may lag skin healing |
Model key actions
- Diagnose PV from flaccid blisters + oral erosions + Nikolsky positivity.[1]
- Dual biopsy: lesional H&E + perilesional DIF (intercellular net-like pattern).[2]
- Start rituximab-based first-line pathway with corticosteroid bridge and supportive care; avoid undertreating mucosal disease.[4][5]
Common errors
- Treating as bullous pemphigoid (wrong IF pattern and steroid strategy).
- Biopsying only the blister roof without perilesional DIF.
- Relying on chronic high-dose steroids without rituximab / steroid-sparing plan.
- Missing nutritional failure from severe stomatitis.
- Failing to consider PNP/PAMS when neoplasm/severe multiorgan mucosal disease is present.
References5ShowHide
- [1]Schmidt E, Kasperkiewicz M, Joly P. Pemphigus. Lancet, 2019.PMID 31498102
- [2]Kasperkiewicz M, Ellebrecht CT, Takahashi H, et al. Pemphigus. Nature Reviews Disease Primers, 2017.PMID 28492232
- [3]Malik AM, Tupchong S, Huang S, et al. An Updated Review of Pemphigus Diseases. Medicina (Kaunas), 2021.PMID 34684117
- [4]Joly P, Horvath B, Patsatsi A, et al. Updated S2K guidelines on the management of pemphigus vulgaris and foliaceus initiated by the European Academy of Dermatology and Venereology (EADV). Journal of the European Academy of Dermatology and Venereology, 2020.PMID 32830877
- [5]Werth VP, Joly P, Mimouni D, et al. Rituximab versus Mycophenolate Mofetil in Patients with Pemphigus Vulgaris. New England Journal of Medicine, 2021.PMID 34097368