Table 2.

Neurofibromatosis 1: Frequency of Select Features

Feature% of Persons w/Feature 1Typical Age of OnsetComment
Café au lait macules>99%Infancy & childhood↑ in number & size during 1st few yrs of life; macules fade in older persons.
Intertrigenous freckling85%Infancy & early childhoodFrequency ↑ w/age during childhood.
Lisch nodules>95%Early childhoodFrequency ↑ w/age during childhood.
Choroidal abnormalities82%-98%Early childhood↑ in number & size during childhood
Optic pathway glioma15%-20%Birth - 6 yrsFrequency lower in adults
Non-optic glioma2%-5%Any ageFrequency lower in children than adults
Cutaneous
neurofibromas		99%Adolescence-adulthoodInfrequent in childhood; variably ↑ in size & number throughout life
Nodular neurofibromas (subcutaneous or deep)~15%AdolescenceFrequency shown is on clinical exam; frequency is 2-3x higher on whole-body MRI.
Plexiform
neurofibroma(s)		~30%Infancy (sometimes congenital) or childhoodFrequency shown is on clinical exam; frequency is ~50% on whole-body MRI.
Malignant peripheral
nerve sheath tumor		8%-13%Adolescence - adulthoodCross-sectional prevalence 2%-5% after mid-childhood
Intellectual disability4%-8%ChildhoodPersists throughout life
Learning difficulties50%-60%ChildhoodPersist throughout life
Behavior issues30%-67%Childhood
Seizures6%-7%Any age
Long bone dysplasia2%Infancy (congenital)
Dystrophic scoliosis5%6-10 yrsRapidly progressive scoliosis due to vertebral dysplasia
Nondystrophic scoliosis5%AdolescenceMilder scoliosis w/o vertebral anomalies
Osteoporosis~20%Mid-adulthoodOsteopenia is frequent at all ages; osteoporosis occurs earlier than in general population but is rare in children & uncommon in young adults
Hypertension≥15%-20%Any agePrevalence greater in adults than children
1.

Many of the features listed in this table have different frequencies at different ages. The table gives life-time cumulative incidence figures that may be higher, and sometimes much higher, than the prevalence at any given age. Most frequencies in this table are from Ferner & Gutmann [2013] or DeBella et al [2000]. References for more recently defined features are given in the discussion of individual features below.

From: Neurofibromatosis 1

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