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Neurofibromatosis Type 1 — SCE Dermatology MCQ

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HardPaediatric DermatologyNeurofibromatosis Type 1SCE Dermatology

A 7-year-old has eight café-au-lait macules and axillary freckling but no neurofibromas, optic pathway glioma, Lisch nodules or affected parent. Which genetic differential is most important before assigning the full NF1 tumour-surveillance burden?

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Correct answer: A — SPRED1-related Legius syndrome, especially while the phenotype remains limited to pigmentary criteria

Explanation lettering: B = shown as A · D = shown as B · E = shown as C · C = shown as D · A = shown as E

B is correct. Legius syndrome from SPRED1 variants can mimic the pigmentary NF1 phenotype with café-au-lait macules and axillary/inguinal freckling but lacks the neurofibromas and characteristic NF1 tumour predisposition. In a young child, NF1 manifestations are age-dependent, so molecular clarification may be important when only pigmentary criteria are present.

Reference: NHS Genomics Education Programme: neurofibromatosis type 1: https://www.genomicseducation.hee.nhs.uk/genotes/knowledge-hub/neurofibromatosis-type-1/