This group of genetic disorders. also known as the phakomatoses,

produces a variety of developmental abnormalities of skin along with

an increased risk of nervous system tumors (Table 3S8~I). These disorders

are inherited as autosomal dominant conditions with variable

penetrance.

NEUROFIBROMATOSIS TYPE I (VON RECKLINGNAUSEN'S OISEASE) NFl is characterized

by cutaneous neurofihromas. pigmented lesions of the skin

called cafe au /ail SpOIS,freckling in non-sun.exposed areas such as

the axilla, hamartomas of the iris termed Lisch nodules. and pseu.

doarthrosis of the tibia. Neurofibromas are benign peripheral nerve

tumors composed of proliferating Schwann cells and fibrobla."ts.They

present as multiple, palpable, rubbery. cutaneous tumors. They are

generally asymptomatic; however, if they grow in an enclosed space,

e.g., the intervertebral foramen. they may produce a compressive ra~

diculopathy or neuropathy, Aqueductal stenosis with hydrocephalus,

scoliosis, short stature. hypertension, epilepsy. and mental retardation

may also occur.

Patients with NFl are at increased risk of developing nervous sys~

tern neoplasms. including plexiform neurofibromas. optic pathway