Derm Cases · Dermatology / Genetics / Neurology / Paediatrics
OSCE — multiple café-au-lait macules: diagnose NF1 and protect against MPNST
An 8-minute OSCE station on café-au-lait macules as a gateway to NF1 diagnosis using revised criteria, surveillance for optic glioma and plexiform neurofibromas, and red-flag pain suggesting MPNST.
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Study tools
Target exams
NEET-PGINICETUSMLEPLABMRCP
Prompt
An 8-minute OSCE station on café-au-lait macules as a gateway to NF1 diagnosis using revised criteria, surveillance for optic glioma and plexiform neurofibromas, and red-flag pain suggesting MPNST.
Brief (to candidate)
A 5-year-old has eight café-au-lait macules >5 mm, freckling in the axillae, and a parent with known NF1. Parents want "cream for the spots." A second stem: adolescent with known NF1 and a painful rapidly enlarging plexiform mass. You have 8 minutes to apply NF1 criteria, plan surveillance, and escalate MPNST concern.
Candidate instructions
- State how CALMs fit into NF1 diagnostic criteria.
- List other major cutaneous/ocular features.
- Outline childhood surveillance priorities.
- Discuss plexiform neurofibroma management concepts (including MEK inhibitors where relevant).
- Recognise MPNST red flags.
Examiner checklist (mark each domain / 10)
| Domain | Key actions expected |
|---|---|
| CALM gateway | ≥6 CALMs (size thresholds by age) is a major criterion — refer genetics; not a cosmetic-only problem when multiple[2][3] |
| NF1 diagnosis | Use revised NIH/Legius consensus criteria (e.g. CALMs, freckling, neurofibromas, Lisch nodules, optic pathway glioma, distinctive bone lesion, parent with NF1, pathogenic NF1 variant) — need sufficient criteria; distinguish Legius syndrome when appropriate[2] |
| Genetics | AD NF1 (chr 17) tumour-suppressor pathway; 50% de novo; counselling for family |
| Surveillance | Growth/BP (renovascular HTN), development/learning, annual ophth for optic pathway glioma in young children, skin exam for neurofibromas/plexiforms, scoliosis/skeletal review as indicated[1][3] |
| Plexiform / MEK | Symptomatic inoperable plexiforms — multidisciplinary; selumetinib (MEK inhibitor) evidence in selected paediatric inoperable plexiform NF1[4][6] |
| MPNST red flag | New pain, rapid growth, hard texture change in plexiform → urgent imaging/biopsy pathway for malignant peripheral nerve sheath tumour |
| Communication | Do not promise creams will "cure NF1 spots"; arrange genetics + long-term follow-up |
Model key actions
- Diagnose probable NF1 from multiple CALMs + freckling + affected parent using revised criteria.[2]
- Set surveillance (eye, BP, development, skin tumours).[3]
- Escalate painful growing plexiform for MPNST work-up; know MEK option for selected plexiforms.[4][6]
Common errors
- Cosmetic dismissal of ≥6 CALMs.
- No ophthalmology surveillance in young children.
- Ignoring new pain in a plexiform mass.
- Confusing NF1 with NF2 (different tumours/criteria).
References5ShowHide
- [1]Tamura R. Current Understanding of Neurofibromatosis Type 1, 2, and Schwannomatosis. International Journal of Molecular Sciences, 2021.PMID 34072574
- [2]Legius E, Messiaen L, Wolkenstein P, et al. Revised diagnostic criteria for neurofibromatosis type 1 and Legius syndrome: an international consensus recommendation. Genetics in medicine : official journal of the American College of Medical Genetics, 2021.PMID 34012067
- [3]Ly KI, Blakeley JO. The Diagnosis and Management of Neurofibromatosis Type 1. The Medical clinics of North America, 2019.PMID 31582003
- [4]Fisher MJ, Blakeley JO, Weiss BD, et al. Management of neurofibromatosis type 1-associated plexiform neurofibromas. Neuro-oncology, 2022.PMID 35657359
- [6]Gross AM, Wolters PL, Dombi E, et al. Selumetinib in Children with Inoperable Plexiform Neurofibromas. New England Journal of Medicine, 2020.PMID 32187457