Table III.
Age of Onset and Frequency of Common NF1 Symptoms
| Symptoms | Typical age at presentation | Frequency |
|---|---|---|
| Café-au-lait spots | Early presentation (occasionally visible at birth; usually present by 2 years of age) | 99% |
| Freckling (axillary, inguinal) | Between 3 and 5 years | >90% |
| Lisch nodules | Late childhood/adolescence | 95% |
| Cutaneous neurofibromas | Variable; may see increase in size and number during adolescence and pregnancy | 0–9 years 14% |
| 10–19 years 44% | ||
| 20–29 years 85% | ||
| >30 years 95% | ||
| Diffuse plexiform neurofibromas | Congenital; manifest early in life | 25% |
| Tibial dysplasia and/or sphenoid dysplasia | Typically visible clinically by 1 year | 1–4% tibial |
| 3–7% sphenoid | ||
| Learning disabilities | May not be identified until school age | 20–50%; MR uncommon (4.8–11%) |
| ADHD | Childhood | 20–40% |
| Optic nerve glioma | Childhood; may be asymptomatic | 15% |
| Malignant peripheral nerve sheath tumor (MPNST) | Average age at diagnosis is 28 years | 4–13% |