Among primary nerve sheath tumors, schwannomas and neurinomas are the
most common. While the schwannomas (neurilemomas) originate in schwann
cells, neurofibromas arise from all the constitutive parts of the ner
ve. The behavior of each tumor is quite different and only neurofibrom
as may present malignant transformation, especially when arising in pa
tients with Von Recklinghausen disease (NF1 with multiple neurofibroma
s).