Derm Cases · Dermatology / Dermatopathology
OSCE — inflammatory dermatopathology: patterns, sampling, DIF, PAS
An 8-minute OSCE on Ackerman-style pattern diagnosis, correct biopsy choice for inflammatory disease, PAS for spongiotic plaques, DIF sampling for blisters, and recognising LCV versus non-specific perivascular inflammation.
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Study tools
Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE on Ackerman-style pattern diagnosis, correct biopsy choice for inflammatory disease, PAS for spongiotic plaques, DIF sampling for blisters, and recognising LCV versus non-specific perivascular inflammation.
Brief (to candidate)
You are teaching a resident how to request and interpret inflammatory skin biopsies. Three scenarios: scaly foot plaque; tense blisters in an elderly man; palpable purpura. In 8 minutes, give a pattern-based sampling and interpretation plan.
[1]Candidate instructions
- State pattern-first method (Ackerman-style).
- Choose biopsy type/depth for each scenario.
- Mention PAS for spongiotic foot disease.
- Plan H&E + perilesional DIF for blisters; contrast PV vs BP DIF patterns.
- Define true LCV histologically.
- Name at least two pitfalls (treated centre, no fat for panniculitis, overcalling MF).
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Pattern method | Starts with dominant reaction pattern then clinical correlation[1][2] |
| Sampling | Punch to adequate depth; deep sample if panniculitis; not shave for deep disease[3] |
| Spongiotic trap | PAS to exclude dermatophyte on foot/hand “eczema”[2] |
| Blister/DIF | Perilesional DIF; intercellular IgG net (PV) vs linear BMZ IgG/C3 (BP)[4] |
| Vasculitis | Fibrinoid necrosis + neutrophilic debris, not mere perivascular lymphs |
| Interface/LP awareness | Can name lichenoid band as LP prototype pattern[5] |
| Safety | Interface necrosis + sick/mucosal patient → SCAR pathway thinking |
Model key actions
- Pattern → special studies → clinicopathologic synthesis.[1]
- Correct DIF site and blister algorithm.[4]
- Do not call every rash “non-specific dermatitis” without PAS/drug history when relevant.
Common errors
- Shave of suspected panniculitis.
- DIF from necrotic blister base only.
- Missing tinea on spongiotic biopsies.
- Labelling mild perivascular lymphocytes as vasculitis.
References5ShowHide
- [1]Ackerman AB. An algorithmic method for histologic diagnosis of inflammatory and neoplastic skin diseases by analysis of their patterns. American Journal of Dermatopathology, 1985.PMID 4025726
- [2]Smith EH, Chan MP. Inflammatory Dermatopathology for General Surgical Pathologists. Clinics in Laboratory Medicine, 2017.PMID 28802506
- [3]Greenwood JD, Merry SP, Boswell CL. Skin Biopsy Techniques. Primary Care, 2022.PMID 35125151
- [4]Schmidt E, Kasperkiewicz M, Joly P. Pemphigus. The Lancet, 2019.PMID 31498102
- [5]Ioannides D, Vakirlis E, Kemeny L, et al. European S1 guidelines on the management of lichen planus. Journal of the European Academy of Dermatology and Venereology, 2020.PMID 32678513