The hallmark of
neurofibromatosis type I in the neonatal period is the presence of cafe
au lait spots (Figure 301.1). The presence of six or more cafe au lait
spots larger than 1 cm in diameter establishes the diagnosis in young
children. Neonates with less than six spots, even if smaller than 1
cm, may have neurofibromatosis because the number and size of the cafe
au lait spots increases after birth.
Two cafe au lait spots in a neonate with neurofibromatosis.
Neurofibromatosis does not
usually produce neurological manifestations in the neonatal period. Nevertheless,
the possibility of dysplastic tumor of the central or peripheral nervous
system should be considered in any patient with neurofibromatosis who
develops a neurological deficit. Careful ophthalmological evaluation should
be performed and, if inconclusive or if an optical disc abnormality is
found, an MRI of the brain should be done to exclude the possibility of
optic glioma. Lisch nodules of the iris and axillary freckling are usually
not present in the neonate. Neurofibromatosis is an autosomal dominant
disorder with 100% penetrance but variable expression. Spontaneous mutations
are frequent. The gene locus is 17q11.2.