Neurofibromatosis type 1
Clinical criteria, age-dependent findings and surveillance in NF1.
Updated: 2026-09-13
Written for clinicians and medical students
This section is a teaching reference for doctors, residents and medical students. It is not patient guidance and not a substitute for clinical examination, and it must not be used for self treatment.
Recognition and diagnosis
- NF1 is autosomal dominant and highly variable. Diagnosis uses revised criteria combining café-au-lait macules, axillary or inguinal freckling, neurofibromas, optic pathway glioma, Lisch nodules or choroidal abnormalities, osseous lesions, a pathogenic NF1 variant and an affected parent [1,2].
- Six or more café-au-lait macules support the diagnosis only when size thresholds and other criteria are considered. Findings accumulate with age, so a young child may need longitudinal review [1].
- Segmental pigment or neurofibromas may represent mosaic NF1. Bilateral pigmentary findings alone also require consideration of Legius syndrome [1].
Surveillance and red flags
- Children need annual clinical review including skin, blood pressure, growth, skeletal assessment, development and vision according to age; routine screening MRI is not recommended in an asymptomatic child [1].
- Persistent pain, rapid enlargement, hardening or neurologic deficit in a plexiform neurofibroma raises concern for malignant peripheral nerve sheath tumour and requires urgent specialist assessment [1].
- Offer genetic counselling. Affected individuals have a 50 percent chance of transmitting the variant, but severity cannot be predicted reliably within a family [2].