Derm Cases · Dermatology / Oncology interface
OSCE — superficial crusted plaques and refractory stomatitis: PF vs paraneoplastic pemphigus
An 8-minute OSCE station distinguishing pemphigus foliaceus from vulgaris and paraneoplastic pemphigus, targeting anti-Dsg1 vs plakin patterns, dual biopsy/ELISA strategy, neoplasm search in PNP, and stepwise therapy including rituximab screening.
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Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station distinguishing pemphigus foliaceus from vulgaris and paraneoplastic pemphigus, targeting anti-Dsg1 vs plakin patterns, dual biopsy/ELISA strategy, neoplasm search in PNP, and stepwise therapy including rituximab screening.
Brief (to candidate)
A 45-year-old has superficial scaly, crusted erosions in a seborrhoeic distribution (face, chest, upper back) without oral ulcers for 3 months. Nikolsky may be positive on lesional skin. A second card describes severe polymorphic stomatitis with lichenoid truncal lesions and weight loss. You have 8 minutes to separate PF from PV and PNP, plan immunofluorescence/serology, and outline management priorities.
Candidate instructions
- Recognise pemphigus foliaceus (superficial, mucosa spared, anti-Dsg1).
- Contrast with pemphigus vulgaris (suprabasal, mucosa common, anti-Dsg3 ± Dsg1).
- Identify paraneoplastic pemphigus red flags and mandate a neoplasm search.
- Plan perilesional DIF + ELISA correctly.
- Outline mild-to-severe PF therapy and pre-rituximab screening.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| PF recognition | Superficial scaly/crusted plaques (seborrhoeic sites), flaccid erosions more than tense bullae, mucosa typically spared (Dsg3 compensation in mucosa)[6] |
| Immunology | PF: anti-Dsg1 IgG; DIF intercellular IgG/C3 often upper epidermis; PV: anti-Dsg3 ± Dsg1, full-thickness ICS pattern more often; mucosa involved in PV[4][6] |
| PNP red flags | Severe refractory stomatitis, polymorphic (lichenoid/EM-like/bullous) rash ± respiratory symptoms → PNP/PAMS; search Castleman, NHL/CLL, thymoma, other neoplasms; watch bronchiolitis obliterans[5] |
| Investigations | Perilesional DIF (Michel’s medium) + lesional H&E; ELISA anti-Dsg1/3; for PNP add plakin immunoblotting/IIF on rat bladder where available and full neoplasm work-up[4][5] |
| PF management | Mild: superpotent topicals ± hydroxychloroquine/sun protection; moderate: prednisolone 0.5–1 mg/kg + steroid-sparing; severe/refractory: rituximab 1 g IV day 1 and 15 with screening[6] |
| PNP priority | Treat underlying neoplasm is cornerstone; rituximab/IVIG/cyclophosphamide combinations for mucocutaneous disease under specialist care[5] |
| Safety | Pre-rituximab: HBV (HBsAg/anti-HBc), HCV/HIV, IGRA, immunoglobulins, vaccines; drug-induced PF (penicillamine/captopril) → stop culprit; endemic fogo selvagem context if relevant travel/origin[1] |
Model key actions
- Diagnose PF when superficial crusted disease spares mucosa and target anti-Dsg1.[6][4]
- Escalate any polymorphic stomatitis + systemic features to PNP work-up and neoplasm search.[5]
- Use perilesional DIF and reserve rituximab for moderate–severe/refractory disease after viral screening.[4][6]
Common errors
- Labelling PF as seborrhoeic dermatitis/impetigo without biopsy/DIF after treatment failure.
- Expecting oral erosions in classic PF (confuses with PV).
- Missing PNP when severe stomatitis dominates.
- Starting rituximab without hepatitis B screening.
- Treating PNP as ordinary PF without neoplasm-directed therapy.
References4ShowHide
- [1]Hans-Filho G, Aoki V, Bittner NRH, et al. Fogo selvagem: endemic pemphigus foliaceus. Anais Brasileiros de Dermatologia, 2018.PMID 30156612
- [4]van Beek N, Holtsche MM, Atefi I, et al. State-of-the-art diagnosis of autoimmune blistering diseases. Frontiers in Immunology, 2024.PMID 38903493
- [5]Anderson HJ, Huang S, Lee JB. Paraneoplastic pemphigus/paraneoplastic autoimmune multiorgan syndrome: Part I. Clinical overview and pathophysiology. Journal of the American Academy of Dermatology, 2024.PMID 37597771
- [6]Malik AM, Tupchong S, Huang S, et al. An Updated Review of Pemphigus Diseases. Medicina (Kaunas), 2021.PMID 34684117