Derm Cases · Dermatology / Dermatopathology
OSCE — order the right stains and DIF without wrecking the sample
An 8-minute OSCE on specimen handling, DIF pattern interpretation, salt-split concepts, special stain selection for infection/amyloid/elastic questions, and therapy pivots.
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Study tools
Target exams
NEET-PGINICETUSMLEPLABMRCPFRCDerm
Prompt
An 8-minute OSCE on specimen handling, DIF pattern interpretation, salt-split concepts, special stain selection for infection/amyloid/elastic questions, and therapy pivots.
Brief (to candidate)
A 72-year-old with tense bullae and a second patient with steroid-treated annular scale are in clinic. You have 8 minutes to plan biopsies/media, interpret classic DIF patterns, and choose special stains that change therapy.
Candidate instructions
- Specify two containers and sites for suspected BP.
- State expected DIF pattern for BP vs pemphigus vs DH.
- Explain salt-split roof vs floor.
- Choose PAS/GMS for tinea incognito suspicion.
- Name one critical pitfall (formalinised DIF specimen).
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Handling | Perilesional Michel DIF + lesional formalin H&E[1][5] |
| Patterns | Fishnet pemphigus; linear BMZ pemphigoid group; granular IgA DH |
| Salt-split | Roof BP-zone vs floor EBA teaching rule[3] |
| Stains | PAS/GMS for fungi; mentions limits of H&E alone[4] |
| Integration | Multimodal AIBD diagnosis (clinic + histo + IF ± serology)[2] |
| Safety | Does not dump IF tissue into formalin |
| Communication | Explains why two biopsies may be needed |
Model key actions
- Write “Michel medium — DIF” on the label before the scalpel starts.
- Match the stain to a clinical question, not a blank panel.
Common errors
- Single formalin pot for everything.
- Biopsying only blister roof for DIF.
- Treating “eczema” with more steroid without PAS when tinea is plausible.
References5ShowHide
- [1]Morrison LH. Direct immunofluorescence microscopy in the diagnosis of autoimmune bullous dermatoses. Clinics in Dermatology, 2001.PMID 11604308
- [2]van Beek N, Holtsche MM, Atefi I, et al. State-of-the-art diagnosis of autoimmune blistering diseases. Frontiers in Immunology, 2024.PMID 38903493
- [3]Woodley DT. Immunofluorescence on salt-split skin for the diagnosis of epidermolysis bullosa acquisita. Archives of Dermatology, 1990.PMID 2405782
- [4]Shalin SC, Ferringer T, Cassarino DS. PAS and GMS utility in dermatopathology: Review of the current medical literature. Journal of Cutaneous Pathology, 2020.PMID 32515092
- [5]Vaughn Jones SA, Palmer I, Bhogal BS, et al. The use of Michel's transport medium for immunofluorescence and immunoelectron microscopy in autoimmune bullous diseases. Acta Dermato-Venereologica, 1995.PMID 7499578