Derm Cases · Dermatology / Procedural diagnostics
OSCE — choose and perform the right skin biopsy
An 8-minute OSCE on selecting shave vs punch vs excisional vs deep sampling, melanoma-preferential complete excision, DIF versus formalin handling, ulcer-edge sampling, and stepwise punch technique.
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Study tools
Target exams
NEET-PGINICETPLABMRCPFRCDerm
Prompt
An 8-minute OSCE on selecting shave vs punch vs excisional vs deep sampling, melanoma-preferential complete excision, DIF versus formalin handling, ulcer-edge sampling, and stepwise punch technique.
Brief (to candidate)
Four clinical vignettes are on the desk (inflammatory rash, melanoma-suspect pigmented lesion, immunobullous disease, panniculitis). Select the correct technique and specimen handling for each, then talk through a punch biopsy as if performing it.
[2]Candidate instructions
- Match each vignette to shave / punch / excise / deep sample.
- State melanoma → complete narrow-margin excision preference and risk of partial biopsy.[3][4]
- State formalin = H&E, Michel = DIF (never formalin for DIF).[5]
- Describe punch steps including stretch perpendicular to RSTL.[1][2]
- Name ulcer edge and panniculitis-to-fat rules.[6]
- Mention labelling and clinical information on the form.
Examiner checklist
| Domain | Key actions expected |
|---|---|
| Inflammatory | Punch full thickness |
| Melanoma | Excisional narrow margin preferred; partial sampling harms diagnosis/staging |
| DIF | Michel medium; separate lesional H&E |
| Panniculitis | Include fat |
| Technique | Mark → LA → stretch → rotate → snip → correct pot |
| Safety | Avoid crush; consent scar/bleed/infection |
Common errors
- Shave for obvious melanoma suspect as default.
- DIF into formalin.
- Superficial sample for panniculitis.
- Biopsy of ulcer centre only.
References6ShowHide
- [1]Greenwood JD, et al. Skin Biopsy Techniques. Prim Care, 2022.PMID 35125151
- [2]Pickett H. Shave and punch biopsy for skin lesions. Am Fam Physician, 2011.PMID 22046939
- [3]Ng JC, et al. The impact of partial biopsy on histopathologic diagnosis of cutaneous melanoma. Arch Dermatol, 2010.PMID 20231492
- [4]Garbe C, et al. European consensus-based interdisciplinary guideline for melanoma. Part 1: Diagnostics: Update 2022. Eur J Cancer, 2022.PMID 35570085
- [5]Kumudhini S, et al. Michel's medium versus honey as transport medium for DIF specimens. J Cutan Pathol, 2019.PMID 31087406
- [6]Rose C, et al. Histopathology of panniculitis--aspects of biopsy techniques. JDDG, 2012.PMID 22084866