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Neurofibromatosis type 1 — RACP Paediatrics MCQ

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EasyGeneticsNeurofibromatosis type 1RACP Paediatrics

A 6-year-old presents with multiple café-au-lait macules (>6, each >5 mm), axillary freckling, and Lisch nodules on slit lamp examination. His father has similar skin findings. What is the most likely diagnosis?

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Correct answer: C — Neurofibromatosis type 1

Six or more café-au-lait macules (≥5 mm prepubertal, ≥15 mm post-pubertal), axillary/inguinal freckling (Crowe sign), and Lisch nodules (iris hamartomas) meet NIH diagnostic criteria for neurofibromatosis type 1 (NF1). It is autosomal dominant (NF1 gene on chromosome 17). Complications include optic pathway gliomas, plexiform neurofibromas, and learning difficulties.

Reference: RACP Paediatric Curriculum – Genetics; RCH Melbourne – 2023 – NF1 CPG