To be given the diagnosis of NF1, an individual must have at least two of the following features. Some people with NF1 have only two, while others can have many of these features:
- Six or more café-au-lait spots over 5 mm in prepubertal patients and over 15 mm after puberty.
- Two or more neurofibromas of any type or one plexiform neurofibroma.
- Freckling in axillary or inguinal regions.
- Optic pathway tumor
- Two or more Lisch nodules
- A distinctive osseous lesion such as sphenoid wing dysplasia or thinning of the cortex of the long bones.
- A first-degree relative with NF1 by the above criteria.
- Also, 50% of patients with NF1 have learning disabilities, making early diagnosis of the disease and intervention even more crucial.
It is proposed that UBOs “Unidentified Bright Objects“ be a diagnostic criterion for NF1 since 43 %-93% of NF children will exhibit areas of increased T2-weighted signal intensity on MRI
The Diagnostic Evaluation and Multidisciplinary Management of Neurofibromatosis 1 and Neurofibromatosis 2 (Journal of the American Medical Association, July 2, 1997 278:51-57)
Possible NF1 Manifestations At Different Life Stages
- Café-au-lait spots. Can occur at any time from birth to age 2.
- Plexiform neurofibromas. In the first year of life, these may present as a subtle soft-tissue enlargement or a large patch of cutaneous hyperpigmentation.
- Tibial dysplasia with anterolateral bowing of the lower leg. Should be referred to an orthopedic surgeon who is familiar with NF1.
- Skinfold freckling. May appear between ages 3 and 5.
- Optic pathway gliomas. Peak incidence is between ages 4 and 6. Annual vision screening, part of standard NF1 surveillance, should detect these lesions and make visual loss rare.
- Two or more Lisch nodules. Occurs in half of patients by age 5.
- Learning disabilities. This common feature of NF1 requires early intervention.
- Attention-deficit disorder. Stimulant medication may be beneficial.
- High blood pressure. Usually associated with renal artery stenosis, but in rare cases may result from pheochromocytomas.
- Plexiform neurofibromas. Tend to be difficult to remove, and may regrow. Surgical treatment and follow-up requires a multidisciplinary team that includes surgeons, radiologists, and oncologists.
- Migraine headaches. May be accompanied by nausea and abdominal pain. Exclude other underlying causes. Standard migraine prophylaxis often helps.
- Dermal neurofibromas. Tend to appear first in late childhood.
- Scoliosis. Can occur in late childhood or adolescence. Spinal fusion may be necessary.
- Dermal neurofibromas. It is impossible to predict the location of lesions or the number that will develop. Some may be surgically removable.
- Hypertension. In adults, this is usually essential hypertension. Persistent hypertension or signs of pheochromocytoma merit further evaluation.
- Malignant peripheral nerve sheath tumors. These can arise from preexisting plexiform neurofibromas. Rapid growth or de novo pain should prompt immediate evaluation. NF1 patients have a 5% lifetime risk of this malignancy.