Derm Cases · Dermatology / Melanoma risk
OSCE — atypical / dysplastic naevus: risk marker, surveillance and FAMMM pathway
An 8-minute OSCE station on atypical (dysplastic) naevi as melanoma risk markers, clinical ABCDE features, biopsy/re-excision thresholds, total-body photography surveillance, and FAMMM/CDKN2A counselling triggers.
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Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on atypical (dysplastic) naevi as melanoma risk markers, clinical ABCDE features, biopsy/re-excision thresholds, total-body photography surveillance, and FAMMM/CDKN2A counselling triggers.
Brief (to candidate)
A 41-year-old fair-skinned man has multiple irregular 6–10 mm moles with variegated colour on the trunk. One lesion has darkened over 3 months. His father died of melanoma at age 48. You have 8 minutes to explain atypical/dysplastic naevi, plan biopsy vs surveillance, and address familial melanoma risk.
[7] [8]Candidate instructions
- Define atypical / dysplastic naevus clinically and conceptually.
- Clarify it is mainly a risk marker rather than inevitable precursor.
- Apply ABCDE / ugly duckling and decide which lesion needs biopsy.
- Outline histologic atypia grades and re-excision concepts for severe atypia / positive margins.
- Plan surveillance (photography, dermoscopy follow-up intervals).
- Recognise FAMMM clues and genetic counselling triggers.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| Definition | Clinically irregular melanocytic naevus (asymmetry, border irregularity, colour variegation, often >5 mm) ± histologic architectural disorder/cytologic atypia; terminology remains debated but exam-relevant as dysplastic/atypical naevus spectrum[2][4] |
| Risk concept | Primarily a melanoma risk marker (especially multiple atypical naevi / phenotype) rather than every lesion progressing to melanoma; personal/family history multiplies risk[1][2] |
| Acute triage | Evolving dark “ugly duckling” → excisional biopsy with narrow margins preferred; do not observe indefinitely when evolution is clear[1][4] |
| Histology / margins | Mild–moderate atypia often observed if completely sampled and clinically stable; severe dysplasia or incomplete removal with residual atypia → consider re-excision to clear margins per local pathology practice[5] |
| Surveillance | Total-body photography ± sequential digital dermoscopy for high-risk phenotype; self-exam teaching; sun protection |
| Familial pathway | Multiple atypical naevi + family melanoma → FAMMM phenotype; discuss CDKN2A / melanoma genetics counselling and intensive surveillance for patient and relatives when indicated[3] |
| Communication | Balanced counselling: increased vigilance without over-excising every mole |
Model key actions
- Label phenotype as multiple atypical naevi with elevated melanoma risk.[1][2]
- Biopsy the evolving lesion; photograph and surveil the rest.[4]
- Offer familial melanoma / genetics pathway given first-degree melanoma death.[3]
Common errors
- Excising every atypical naevus “prophylactically.”
- Watching an evolving lesion for many months without biopsy.
- Ignoring family history and hereditary melanoma risk.
- Confusing mild histologic dysplasia with melanoma diagnosis.
- Failing to re-excise severely dysplastic incomplete specimens.
References8ShowHide
- [1]Zhang Y, Ostrowski SM, Fisher DE. Nevi and Melanoma. Hematology/oncology clinics of North America, 2024.PMID 38880666
- [2]Drozdowski R, Spaccarelli N, Peters MS, et al. Dysplastic nevus part I: Historical perspective, classification, and epidemiology. Journal of the American Academy of Dermatology, 2023.PMID 36038073
- [3]Newton-Bishop J, Bishop DT, Harland M. Melanoma Genomics. Acta dermato-venereologica, 2020.PMID 32346746
- [4]Friedman RJ, Farber MJ, Warycha MA, et al. The 'dysplastic' nevus. Clinics in Dermatology, 2009.PMID 19095156
- [5]Bierhoff E. Dysplastic melanocytic nevus. Der Pathologe, 2015.PMID 25591417
- [6]Jen M, Murphy M, Grant-Kels JM. Childhood melanoma. Clinics in Dermatology, 2009.PMID 19880040
- [7]Kim CC, Swetter SM, Curiel-Lewandrowski C, et al. Addressing the knowledge gap in clinical recommendations for management and complete excision of clinically atypical nevi/dysplastic nevi: Pigmented Lesion Subcommittee consensus statement JAMA Dermatol, 2015.PMID 25409291
- [8]Kim CC, Swetter SM, Curiel-Lewandrowski C, et al. Addressing the knowledge gap in clinical recommendations for management and complete excision of clinically atypical nevi/dysplastic nevi: Pigmented Lesion Subcommittee consensus statement JAMA Dermatol, 2015.PMID 25409291